G2 SEC examination decisions differ in how costly they are to undo. A pencil mark, estimate or temporary diagram is cheap to reverse. Spending ten minutes, rounding away precision, discarding a valid branch or committing to the wrong source can be expensive or impossible to recover from later.
This one-hundred-and-twenty-eighth Learner’s Guide develops reversible-versus-irreversible move control across K200 English, K210 Mathematics and K223–K225 Science. It builds on Vol 0120 Answer-State Control and Vol 0116 Dependency Blast Radius.
The reversibility test
Before a decision, ask how easily it can be undone, what information would be lost, and how much future work will depend on it. Prefer reversible exploratory moves while uncertainty is high; delay irreversible commitments until the evidence or model is strong enough.
1. underline a command word
For underline a command word, classify the move as cheaply reversible, moderately costly to reverse, or effectively irreversible under examination time. Then name the information or time that would be lost if the decision proved wrong.
For practice, compare two routes: one that preserves options and one that commits early. Identify the evidence threshold that should trigger commitment. This trains learners to explore without becoming indecisive and to commit without becoming reckless.
A reversible move should create information: a sketch should reveal structure, a candidate interpretation should be tested, and a parked question should preserve state. Reversibility is useful only when it reduces uncertainty or protects future options.
2. circle a source boundary
For circle a source boundary, classify the move as cheaply reversible, moderately costly to reverse, or effectively irreversible under examination time. Then name the information or time that would be lost if the decision proved wrong.
For practice, compare two routes: one that preserves options and one that commits early. Identify the evidence threshold that should trigger commitment. This trains learners to explore without becoming indecisive and to commit without becoming reckless.
A reversible move should create information: a sketch should reveal structure, a candidate interpretation should be tested, and a parked question should preserve state. Reversibility is useful only when it reduces uncertainty or protects future options.
3. mark a denominator
For mark a denominator, classify the move as cheaply reversible, moderately costly to reverse, or effectively irreversible under examination time. Then name the information or time that would be lost if the decision proved wrong.
For practice, compare two routes: one that preserves options and one that commits early. Identify the evidence threshold that should trigger commitment. This trains learners to explore without becoming indecisive and to commit without becoming reckless.
A reversible move should create information: a sketch should reveal structure, a candidate interpretation should be tested, and a parked question should preserve state. Reversibility is useful only when it reduces uncertainty or protects future options.
4. write a unit
For write a unit, classify the move as cheaply reversible, moderately costly to reverse, or effectively irreversible under examination time. Then name the information or time that would be lost if the decision proved wrong.
For practice, compare two routes: one that preserves options and one that commits early. Identify the evidence threshold that should trigger commitment. This trains learners to explore without becoming indecisive and to commit without becoming reckless.
A reversible move should create information: a sketch should reveal structure, a candidate interpretation should be tested, and a parked question should preserve state. Reversibility is useful only when it reduces uncertainty or protects future options.
5. make a rough estimate
For make a rough estimate, classify the move as cheaply reversible, moderately costly to reverse, or effectively irreversible under examination time. Then name the information or time that would be lost if the decision proved wrong.
For practice, compare two routes: one that preserves options and one that commits early. Identify the evidence threshold that should trigger commitment. This trains learners to explore without becoming indecisive and to commit without becoming reckless.
A reversible move should create information: a sketch should reveal structure, a candidate interpretation should be tested, and a parked question should preserve state. Reversibility is useful only when it reduces uncertainty or protects future options.
6. draw a temporary diagram
For draw a temporary diagram, classify the move as cheaply reversible, moderately costly to reverse, or effectively irreversible under examination time. Then name the information or time that would be lost if the decision proved wrong.
For practice, compare two routes: one that preserves options and one that commits early. Identify the evidence threshold that should trigger commitment. This trains learners to explore without becoming indecisive and to commit without becoming reckless.
A reversible move should create information: a sketch should reveal structure, a candidate interpretation should be tested, and a parked question should preserve state. Reversibility is useful only when it reduces uncertainty or protects future options.
7. list two candidate referents
For list two candidate referents, classify the move as cheaply reversible, moderately costly to reverse, or effectively irreversible under examination time. Then name the information or time that would be lost if the decision proved wrong.
For practice, compare two routes: one that preserves options and one that commits early. Identify the evidence threshold that should trigger commitment. This trains learners to explore without becoming indecisive and to commit without becoming reckless.
A reversible move should create information: a sketch should reveal structure, a candidate interpretation should be tested, and a parked question should preserve state. Reversibility is useful only when it reduces uncertainty or protects future options.
8. park a question
For park a question, classify the move as cheaply reversible, moderately costly to reverse, or effectively irreversible under examination time. Then name the information or time that would be lost if the decision proved wrong.
For practice, compare two routes: one that preserves options and one that commits early. Identify the evidence threshold that should trigger commitment. This trains learners to explore without becoming indecisive and to commit without becoming reckless.
A reversible move should create information: a sketch should reveal structure, a candidate interpretation should be tested, and a parked question should preserve state. Reversibility is useful only when it reduces uncertainty or protects future options.
9. change representation
For change representation, classify the move as cheaply reversible, moderately costly to reverse, or effectively irreversible under examination time. Then name the information or time that would be lost if the decision proved wrong.
For practice, compare two routes: one that preserves options and one that commits early. Identify the evidence threshold that should trigger commitment. This trains learners to explore without becoming indecisive and to commit without becoming reckless.
A reversible move should create information: a sketch should reveal structure, a candidate interpretation should be tested, and a parked question should preserve state. Reversibility is useful only when it reduces uncertainty or protects future options.
10. test an MCQ option
For test an MCQ option, classify the move as cheaply reversible, moderately costly to reverse, or effectively irreversible under examination time. Then name the information or time that would be lost if the decision proved wrong.
For practice, compare two routes: one that preserves options and one that commits early. Identify the evidence threshold that should trigger commitment. This trains learners to explore without becoming indecisive and to commit without becoming reckless.
A reversible move should create information: a sketch should reveal structure, a candidate interpretation should be tested, and a parked question should preserve state. Reversibility is useful only when it reduces uncertainty or protects future options.
11. write a provisional equation
For write a provisional equation, classify the move as cheaply reversible, moderately costly to reverse, or effectively irreversible under examination time. Then name the information or time that would be lost if the decision proved wrong.
For practice, compare two routes: one that preserves options and one that commits early. Identify the evidence threshold that should trigger commitment. This trains learners to explore without becoming indecisive and to commit without becoming reckless.
A reversible move should create information: a sketch should reveal structure, a candidate interpretation should be tested, and a parked question should preserve state. Reversibility is useful only when it reduces uncertainty or protects future options.
12. write a provisional inference
For write a provisional inference, classify the move as cheaply reversible, moderately costly to reverse, or effectively irreversible under examination time. Then name the information or time that would be lost if the decision proved wrong.
For practice, compare two routes: one that preserves options and one that commits early. Identify the evidence threshold that should trigger commitment. This trains learners to explore without becoming indecisive and to commit without becoming reckless.
A reversible move should create information: a sketch should reveal structure, a candidate interpretation should be tested, and a parked question should preserve state. Reversibility is useful only when it reduces uncertainty or protects future options.
13. mark an uncertainty
For mark an uncertainty, classify the move as cheaply reversible, moderately costly to reverse, or effectively irreversible under examination time. Then name the information or time that would be lost if the decision proved wrong.
For practice, compare two routes: one that preserves options and one that commits early. Identify the evidence threshold that should trigger commitment. This trains learners to explore without becoming indecisive and to commit without becoming reckless.
A reversible move should create information: a sketch should reveal structure, a candidate interpretation should be tested, and a parked question should preserve state. Reversibility is useful only when it reduces uncertainty or protects future options.
14. add a checkpoint
For add a checkpoint, classify the move as cheaply reversible, moderately costly to reverse, or effectively irreversible under examination time. Then name the information or time that would be lost if the decision proved wrong.
For practice, compare two routes: one that preserves options and one that commits early. Identify the evidence threshold that should trigger commitment. This trains learners to explore without becoming indecisive and to commit without becoming reckless.
A reversible move should create information: a sketch should reveal structure, a candidate interpretation should be tested, and a parked question should preserve state. Reversibility is useful only when it reduces uncertainty or protects future options.
15. choose a source quote
For choose a source quote, classify the move as cheaply reversible, moderately costly to reverse, or effectively irreversible under examination time. Then name the information or time that would be lost if the decision proved wrong.
For practice, compare two routes: one that preserves options and one that commits early. Identify the evidence threshold that should trigger commitment. This trains learners to explore without becoming indecisive and to commit without becoming reckless.
A reversible move should create information: a sketch should reveal structure, a candidate interpretation should be tested, and a parked question should preserve state. Reversibility is useful only when it reduces uncertainty or protects future options.
16. cross out a candidate answer
For cross out a candidate answer, classify the move as cheaply reversible, moderately costly to reverse, or effectively irreversible under examination time. Then name the information or time that would be lost if the decision proved wrong.
For practice, compare two routes: one that preserves options and one that commits early. Identify the evidence threshold that should trigger commitment. This trains learners to explore without becoming indecisive and to commit without becoming reckless.
A reversible move should create information: a sketch should reveal structure, a candidate interpretation should be tested, and a parked question should preserve state. Reversibility is useful only when it reduces uncertainty or protects future options.
17. commit to an MCQ option
For commit to an MCQ option, classify the move as cheaply reversible, moderately costly to reverse, or effectively irreversible under examination time. Then name the information or time that would be lost if the decision proved wrong.
For practice, compare two routes: one that preserves options and one that commits early. Identify the evidence threshold that should trigger commitment. This trains learners to explore without becoming indecisive and to commit without becoming reckless.
A reversible move should create information: a sketch should reveal structure, a candidate interpretation should be tested, and a parked question should preserve state. Reversibility is useful only when it reduces uncertainty or protects future options.
18. transfer final answer
For transfer final answer, classify the move as cheaply reversible, moderately costly to reverse, or effectively irreversible under examination time. Then name the information or time that would be lost if the decision proved wrong.
For practice, compare two routes: one that preserves options and one that commits early. Identify the evidence threshold that should trigger commitment. This trains learners to explore without becoming indecisive and to commit without becoming reckless.
A reversible move should create information: a sketch should reveal structure, a candidate interpretation should be tested, and a parked question should preserve state. Reversibility is useful only when it reduces uncertainty or protects future options.
19. round a final value
For round a final value, classify the move as cheaply reversible, moderately costly to reverse, or effectively irreversible under examination time. Then name the information or time that would be lost if the decision proved wrong.
For practice, compare two routes: one that preserves options and one that commits early. Identify the evidence threshold that should trigger commitment. This trains learners to explore without becoming indecisive and to commit without becoming reckless.
A reversible move should create information: a sketch should reveal structure, a candidate interpretation should be tested, and a parked question should preserve state. Reversibility is useful only when it reduces uncertainty or protects future options.
20. delete a summary point
For delete a summary point, classify the move as cheaply reversible, moderately costly to reverse, or effectively irreversible under examination time. Then name the information or time that would be lost if the decision proved wrong.
For practice, compare two routes: one that preserves options and one that commits early. Identify the evidence threshold that should trigger commitment. This trains learners to explore without becoming indecisive and to commit without becoming reckless.
A reversible move should create information: a sketch should reveal structure, a candidate interpretation should be tested, and a parked question should preserve state. Reversibility is useful only when it reduces uncertainty or protects future options.
21. use a limited word budget
For use a limited word budget, classify the move as cheaply reversible, moderately costly to reverse, or effectively irreversible under examination time. Then name the information or time that would be lost if the decision proved wrong.
For practice, compare two routes: one that preserves options and one that commits early. Identify the evidence threshold that should trigger commitment. This trains learners to explore without becoming indecisive and to commit without becoming reckless.
A reversible move should create information: a sketch should reveal structure, a candidate interpretation should be tested, and a parked question should preserve state. Reversibility is useful only when it reduces uncertainty or protects future options.
22. spend five more minutes
For spend five more minutes, classify the move as cheaply reversible, moderately costly to reverse, or effectively irreversible under examination time. Then name the information or time that would be lost if the decision proved wrong.
For practice, compare two routes: one that preserves options and one that commits early. Identify the evidence threshold that should trigger commitment. This trains learners to explore without becoming indecisive and to commit without becoming reckless.
A reversible move should create information: a sketch should reveal structure, a candidate interpretation should be tested, and a parked question should preserve state. Reversibility is useful only when it reduces uncertainty or protects future options.
23. skip a question temporarily
For skip a question temporarily, classify the move as cheaply reversible, moderately costly to reverse, or effectively irreversible under examination time. Then name the information or time that would be lost if the decision proved wrong.
For practice, compare two routes: one that preserves options and one that commits early. Identify the evidence threshold that should trigger commitment. This trains learners to explore without becoming indecisive and to commit without becoming reckless.
A reversible move should create information: a sketch should reveal structure, a candidate interpretation should be tested, and a parked question should preserve state. Reversibility is useful only when it reduces uncertainty or protects future options.
24. choose one optional question
For choose one optional question, classify the move as cheaply reversible, moderately costly to reverse, or effectively irreversible under examination time. Then name the information or time that would be lost if the decision proved wrong.
For practice, compare two routes: one that preserves options and one that commits early. Identify the evidence threshold that should trigger commitment. This trains learners to explore without becoming indecisive and to commit without becoming reckless.
A reversible move should create information: a sketch should reveal structure, a candidate interpretation should be tested, and a parked question should preserve state. Reversibility is useful only when it reduces uncertainty or protects future options.
25. write on final response line
For write on final response line, classify the move as cheaply reversible, moderately costly to reverse, or effectively irreversible under examination time. Then name the information or time that would be lost if the decision proved wrong.
For practice, compare two routes: one that preserves options and one that commits early. Identify the evidence threshold that should trigger commitment. This trains learners to explore without becoming indecisive and to commit without becoming reckless.
A reversible move should create information: a sketch should reveal structure, a candidate interpretation should be tested, and a parked question should preserve state. Reversibility is useful only when it reduces uncertainty or protects future options.
26. change a graph scale already drawn
For change a graph scale already drawn, classify the move as cheaply reversible, moderately costly to reverse, or effectively irreversible under examination time. Then name the information or time that would be lost if the decision proved wrong.
For practice, compare two routes: one that preserves options and one that commits early. Identify the evidence threshold that should trigger commitment. This trains learners to explore without becoming indecisive and to commit without becoming reckless.
A reversible move should create information: a sketch should reveal structure, a candidate interpretation should be tested, and a parked question should preserve state. Reversibility is useful only when it reduces uncertainty or protects future options.
27. rewrite a whole paragraph
For rewrite a whole paragraph, classify the move as cheaply reversible, moderately costly to reverse, or effectively irreversible under examination time. Then name the information or time that would be lost if the decision proved wrong.
For practice, compare two routes: one that preserves options and one that commits early. Identify the evidence threshold that should trigger commitment. This trains learners to explore without becoming indecisive and to commit without becoming reckless.
A reversible move should create information: a sketch should reveal structure, a candidate interpretation should be tested, and a parked question should preserve state. Reversibility is useful only when it reduces uncertainty or protects future options.
28. erase correct working
For erase correct working, classify the move as cheaply reversible, moderately costly to reverse, or effectively irreversible under examination time. Then name the information or time that would be lost if the decision proved wrong.
For practice, compare two routes: one that preserves options and one that commits early. Identify the evidence threshold that should trigger commitment. This trains learners to explore without becoming indecisive and to commit without becoming reckless.
A reversible move should create information: a sketch should reveal structure, a candidate interpretation should be tested, and a parked question should preserve state. Reversibility is useful only when it reduces uncertainty or protects future options.
29. apply a non-reversible algebra step
For apply a non-reversible algebra step, classify the move as cheaply reversible, moderately costly to reverse, or effectively irreversible under examination time. Then name the information or time that would be lost if the decision proved wrong.
For practice, compare two routes: one that preserves options and one that commits early. Identify the evidence threshold that should trigger commitment. This trains learners to explore without becoming indecisive and to commit without becoming reckless.
A reversible move should create information: a sketch should reveal structure, a candidate interpretation should be tested, and a parked question should preserve state. Reversibility is useful only when it reduces uncertainty or protects future options.
30. square both sides
For square both sides, classify the move as cheaply reversible, moderately costly to reverse, or effectively irreversible under examination time. Then name the information or time that would be lost if the decision proved wrong.
For practice, compare two routes: one that preserves options and one that commits early. Identify the evidence threshold that should trigger commitment. This trains learners to explore without becoming indecisive and to commit without becoming reckless.
A reversible move should create information: a sketch should reveal structure, a candidate interpretation should be tested, and a parked question should preserve state. Reversibility is useful only when it reduces uncertainty or protects future options.
31. round intermediate values
For round intermediate values, classify the move as cheaply reversible, moderately costly to reverse, or effectively irreversible under examination time. Then name the information or time that would be lost if the decision proved wrong.
For practice, compare two routes: one that preserves options and one that commits early. Identify the evidence threshold that should trigger commitment. This trains learners to explore without becoming indecisive and to commit without becoming reckless.
A reversible move should create information: a sketch should reveal structure, a candidate interpretation should be tested, and a parked question should preserve state. Reversibility is useful only when it reduces uncertainty or protects future options.
32. cancel a variable expression
For cancel a variable expression, classify the move as cheaply reversible, moderately costly to reverse, or effectively irreversible under examination time. Then name the information or time that would be lost if the decision proved wrong.
For practice, compare two routes: one that preserves options and one that commits early. Identify the evidence threshold that should trigger commitment. This trains learners to explore without becoming indecisive and to commit without becoming reckless.
A reversible move should create information: a sketch should reveal structure, a candidate interpretation should be tested, and a parked question should preserve state. Reversibility is useful only when it reduces uncertainty or protects future options.
33. divide by an unknown-sign quantity
For divide by an unknown-sign quantity, classify the move as cheaply reversible, moderately costly to reverse, or effectively irreversible under examination time. Then name the information or time that would be lost if the decision proved wrong.
For practice, compare two routes: one that preserves options and one that commits early. Identify the evidence threshold that should trigger commitment. This trains learners to explore without becoming indecisive and to commit without becoming reckless.
A reversible move should create information: a sketch should reveal structure, a candidate interpretation should be tested, and a parked question should preserve state. Reversibility is useful only when it reduces uncertainty or protects future options.
34. generalise from sample
For generalise from sample, classify the move as cheaply reversible, moderately costly to reverse, or effectively irreversible under examination time. Then name the information or time that would be lost if the decision proved wrong.
For practice, compare two routes: one that preserves options and one that commits early. Identify the evidence threshold that should trigger commitment. This trains learners to explore without becoming indecisive and to commit without becoming reckless.
A reversible move should create information: a sketch should reveal structure, a candidate interpretation should be tested, and a parked question should preserve state. Reversibility is useful only when it reduces uncertainty or protects future options.
35. state a causal conclusion
For state a causal conclusion, classify the move as cheaply reversible, moderately costly to reverse, or effectively irreversible under examination time. Then name the information or time that would be lost if the decision proved wrong.
For practice, compare two routes: one that preserves options and one that commits early. Identify the evidence threshold that should trigger commitment. This trains learners to explore without becoming indecisive and to commit without becoming reckless.
A reversible move should create information: a sketch should reveal structure, a candidate interpretation should be tested, and a parked question should preserve state. Reversibility is useful only when it reduces uncertainty or protects future options.
36. attribute claim to source
For attribute claim to source, classify the move as cheaply reversible, moderately costly to reverse, or effectively irreversible under examination time. Then name the information or time that would be lost if the decision proved wrong.
For practice, compare two routes: one that preserves options and one that commits early. Identify the evidence threshold that should trigger commitment. This trains learners to explore without becoming indecisive and to commit without becoming reckless.
A reversible move should create information: a sketch should reveal structure, a candidate interpretation should be tested, and a parked question should preserve state. Reversibility is useful only when it reduces uncertainty or protects future options.
37. label a control
For label a control, classify the move as cheaply reversible, moderately costly to reverse, or effectively irreversible under examination time. Then name the information or time that would be lost if the decision proved wrong.
For practice, compare two routes: one that preserves options and one that commits early. Identify the evidence threshold that should trigger commitment. This trains learners to explore without becoming indecisive and to commit without becoming reckless.
A reversible move should create information: a sketch should reveal structure, a candidate interpretation should be tested, and a parked question should preserve state. Reversibility is useful only when it reduces uncertainty or protects future options.
38. choose a model
For choose a model, classify the move as cheaply reversible, moderately costly to reverse, or effectively irreversible under examination time. Then name the information or time that would be lost if the decision proved wrong.
For practice, compare two routes: one that preserves options and one that commits early. Identify the evidence threshold that should trigger commitment. This trains learners to explore without becoming indecisive and to commit without becoming reckless.
A reversible move should create information: a sketch should reveal structure, a candidate interpretation should be tested, and a parked question should preserve state. Reversibility is useful only when it reduces uncertainty or protects future options.
39. discard an outlier
For discard an outlier, classify the move as cheaply reversible, moderately costly to reverse, or effectively irreversible under examination time. Then name the information or time that would be lost if the decision proved wrong.
For practice, compare two routes: one that preserves options and one that commits early. Identify the evidence threshold that should trigger commitment. This trains learners to explore without becoming indecisive and to commit without becoming reckless.
A reversible move should create information: a sketch should reveal structure, a candidate interpretation should be tested, and a parked question should preserve state. Reversibility is useful only when it reduces uncertainty or protects future options.
40. combine two categories
For combine two categories, classify the move as cheaply reversible, moderately costly to reverse, or effectively irreversible under examination time. Then name the information or time that would be lost if the decision proved wrong.
For practice, compare two routes: one that preserves options and one that commits early. Identify the evidence threshold that should trigger commitment. This trains learners to explore without becoming indecisive and to commit without becoming reckless.
A reversible move should create information: a sketch should reveal structure, a candidate interpretation should be tested, and a parked question should preserve state. Reversibility is useful only when it reduces uncertainty or protects future options.
41. merge summary points
For merge summary points, classify the move as cheaply reversible, moderately costly to reverse, or effectively irreversible under examination time. Then name the information or time that would be lost if the decision proved wrong.
For practice, compare two routes: one that preserves options and one that commits early. Identify the evidence threshold that should trigger commitment. This trains learners to explore without becoming indecisive and to commit without becoming reckless.
A reversible move should create information: a sketch should reveal structure, a candidate interpretation should be tested, and a parked question should preserve state. Reversibility is useful only when it reduces uncertainty or protects future options.
42. convert exact to decimal
For convert exact to decimal, classify the move as cheaply reversible, moderately costly to reverse, or effectively irreversible under examination time. Then name the information or time that would be lost if the decision proved wrong.
For practice, compare two routes: one that preserves options and one that commits early. Identify the evidence threshold that should trigger commitment. This trains learners to explore without becoming indecisive and to commit without becoming reckless.
A reversible move should create information: a sketch should reveal structure, a candidate interpretation should be tested, and a parked question should preserve state. Reversibility is useful only when it reduces uncertainty or protects future options.
43. choose minimum integer
For choose minimum integer, classify the move as cheaply reversible, moderately costly to reverse, or effectively irreversible under examination time. Then name the information or time that would be lost if the decision proved wrong.
For practice, compare two routes: one that preserves options and one that commits early. Identify the evidence threshold that should trigger commitment. This trains learners to explore without becoming indecisive and to commit without becoming reckless.
A reversible move should create information: a sketch should reveal structure, a candidate interpretation should be tested, and a parked question should preserve state. Reversibility is useful only when it reduces uncertainty or protects future options.
44. choose maximum integer
For choose maximum integer, classify the move as cheaply reversible, moderately costly to reverse, or effectively irreversible under examination time. Then name the information or time that would be lost if the decision proved wrong.
For practice, compare two routes: one that preserves options and one that commits early. Identify the evidence threshold that should trigger commitment. This trains learners to explore without becoming indecisive and to commit without becoming reckless.
A reversible move should create information: a sketch should reveal structure, a candidate interpretation should be tested, and a parked question should preserve state. Reversibility is useful only when it reduces uncertainty or protects future options.
45. assume a diagram is to scale
For assume a diagram is to scale, classify the move as cheaply reversible, moderately costly to reverse, or effectively irreversible under examination time. Then name the information or time that would be lost if the decision proved wrong.
For practice, compare two routes: one that preserves options and one that commits early. Identify the evidence threshold that should trigger commitment. This trains learners to explore without becoming indecisive and to commit without becoming reckless.
A reversible move should create information: a sketch should reveal structure, a candidate interpretation should be tested, and a parked question should preserve state. Reversibility is useful only when it reduces uncertainty or protects future options.
46. assume equal likelihood
For assume equal likelihood, classify the move as cheaply reversible, moderately costly to reverse, or effectively irreversible under examination time. Then name the information or time that would be lost if the decision proved wrong.
For practice, compare two routes: one that preserves options and one that commits early. Identify the evidence threshold that should trigger commitment. This trains learners to explore without becoming indecisive and to commit without becoming reckless.
A reversible move should create information: a sketch should reveal structure, a candidate interpretation should be tested, and a parked question should preserve state. Reversibility is useful only when it reduces uncertainty or protects future options.
47. assume constant rate
For assume constant rate, classify the move as cheaply reversible, moderately costly to reverse, or effectively irreversible under examination time. Then name the information or time that would be lost if the decision proved wrong.
For practice, compare two routes: one that preserves options and one that commits early. Identify the evidence threshold that should trigger commitment. This trains learners to explore without becoming indecisive and to commit without becoming reckless.
A reversible move should create information: a sketch should reveal structure, a candidate interpretation should be tested, and a parked question should preserve state. Reversibility is useful only when it reduces uncertainty or protects future options.
48. assume linearity
For assume linearity, classify the move as cheaply reversible, moderately costly to reverse, or effectively irreversible under examination time. Then name the information or time that would be lost if the decision proved wrong.
For practice, compare two routes: one that preserves options and one that commits early. Identify the evidence threshold that should trigger commitment. This trains learners to explore without becoming indecisive and to commit without becoming reckless.
A reversible move should create information: a sketch should reveal structure, a candidate interpretation should be tested, and a parked question should preserve state. Reversibility is useful only when it reduces uncertainty or protects future options.
49. assume no friction
For assume no friction, classify the move as cheaply reversible, moderately costly to reverse, or effectively irreversible under examination time. Then name the information or time that would be lost if the decision proved wrong.
For practice, compare two routes: one that preserves options and one that commits early. Identify the evidence threshold that should trigger commitment. This trains learners to explore without becoming indecisive and to commit without becoming reckless.
A reversible move should create information: a sketch should reveal structure, a candidate interpretation should be tested, and a parked question should preserve state. Reversibility is useful only when it reduces uncertainty or protects future options.
50. assume representative sample
For assume representative sample, classify the move as cheaply reversible, moderately costly to reverse, or effectively irreversible under examination time. Then name the information or time that would be lost if the decision proved wrong.
For practice, compare two routes: one that preserves options and one that commits early. Identify the evidence threshold that should trigger commitment. This trains learners to explore without becoming indecisive and to commit without becoming reckless.
A reversible move should create information: a sketch should reveal structure, a candidate interpretation should be tested, and a parked question should preserve state. Reversibility is useful only when it reduces uncertainty or protects future options.
51. use later evidence for earlier motive
For use later evidence for earlier motive, classify the move as cheaply reversible, moderately costly to reverse, or effectively irreversible under examination time. Then name the information or time that would be lost if the decision proved wrong.
For practice, compare two routes: one that preserves options and one that commits early. Identify the evidence threshold that should trigger commitment. This trains learners to explore without becoming indecisive and to commit without becoming reckless.
A reversible move should create information: a sketch should reveal structure, a candidate interpretation should be tested, and a parked question should preserve state. Reversibility is useful only when it reduces uncertainty or protects future options.
52. change tense in paraphrase
For change tense in paraphrase, classify the move as cheaply reversible, moderately costly to reverse, or effectively irreversible under examination time. Then name the information or time that would be lost if the decision proved wrong.
For practice, compare two routes: one that preserves options and one that commits early. Identify the evidence threshold that should trigger commitment. This trains learners to explore without becoming indecisive and to commit without becoming reckless.
A reversible move should create information: a sketch should reveal structure, a candidate interpretation should be tested, and a parked question should preserve state. Reversibility is useful only when it reduces uncertainty or protects future options.
53. strengthen may to will
For strengthen may to will, classify the move as cheaply reversible, moderately costly to reverse, or effectively irreversible under examination time. Then name the information or time that would be lost if the decision proved wrong.
For practice, compare two routes: one that preserves options and one that commits early. Identify the evidence threshold that should trigger commitment. This trains learners to explore without becoming indecisive and to commit without becoming reckless.
A reversible move should create information: a sketch should reveal structure, a candidate interpretation should be tested, and a parked question should preserve state. Reversibility is useful only when it reduces uncertainty or protects future options.
54. strengthen most to all
For strengthen most to all, classify the move as cheaply reversible, moderately costly to reverse, or effectively irreversible under examination time. Then name the information or time that would be lost if the decision proved wrong.
For practice, compare two routes: one that preserves options and one that commits early. Identify the evidence threshold that should trigger commitment. This trains learners to explore without becoming indecisive and to commit without becoming reckless.
A reversible move should create information: a sketch should reveal structure, a candidate interpretation should be tested, and a parked question should preserve state. Reversibility is useful only when it reduces uncertainty or protects future options.
55. replace associated with caused by
For replace associated with caused by, classify the move as cheaply reversible, moderately costly to reverse, or effectively irreversible under examination time. Then name the information or time that would be lost if the decision proved wrong.
For practice, compare two routes: one that preserves options and one that commits early. Identify the evidence threshold that should trigger commitment. This trains learners to explore without becoming indecisive and to commit without becoming reckless.
A reversible move should create information: a sketch should reveal structure, a candidate interpretation should be tested, and a parked question should preserve state. Reversibility is useful only when it reduces uncertainty or protects future options.
56. choose a comparison denominator
For choose a comparison denominator, classify the move as cheaply reversible, moderately costly to reverse, or effectively irreversible under examination time. Then name the information or time that would be lost if the decision proved wrong.
For practice, compare two routes: one that preserves options and one that commits early. Identify the evidence threshold that should trigger commitment. This trains learners to explore without becoming indecisive and to commit without becoming reckless.
A reversible move should create information: a sketch should reveal structure, a candidate interpretation should be tested, and a parked question should preserve state. Reversibility is useful only when it reduces uncertainty or protects future options.
57. choose rate direction
For choose rate direction, classify the move as cheaply reversible, moderately costly to reverse, or effectively irreversible under examination time. Then name the information or time that would be lost if the decision proved wrong.
For practice, compare two routes: one that preserves options and one that commits early. Identify the evidence threshold that should trigger commitment. This trains learners to explore without becoming indecisive and to commit without becoming reckless.
A reversible move should create information: a sketch should reveal structure, a candidate interpretation should be tested, and a parked question should preserve state. Reversibility is useful only when it reduces uncertainty or protects future options.
58. choose currency conversion direction
For choose currency conversion direction, classify the move as cheaply reversible, moderately costly to reverse, or effectively irreversible under examination time. Then name the information or time that would be lost if the decision proved wrong.
For practice, compare two routes: one that preserves options and one that commits early. Identify the evidence threshold that should trigger commitment. This trains learners to explore without becoming indecisive and to commit without becoming reckless.
A reversible move should create information: a sketch should reveal structure, a candidate interpretation should be tested, and a parked question should preserve state. Reversibility is useful only when it reduces uncertainty or protects future options.
59. choose probability universe
For choose probability universe, classify the move as cheaply reversible, moderately costly to reverse, or effectively irreversible under examination time. Then name the information or time that would be lost if the decision proved wrong.
For practice, compare two routes: one that preserves options and one that commits early. Identify the evidence threshold that should trigger commitment. This trains learners to explore without becoming indecisive and to commit without becoming reckless.
A reversible move should create information: a sketch should reveal structure, a candidate interpretation should be tested, and a parked question should preserve state. Reversibility is useful only when it reduces uncertainty or protects future options.
60. choose case branch
For choose case branch, classify the move as cheaply reversible, moderately costly to reverse, or effectively irreversible under examination time. Then name the information or time that would be lost if the decision proved wrong.
For practice, compare two routes: one that preserves options and one that commits early. Identify the evidence threshold that should trigger commitment. This trains learners to explore without becoming indecisive and to commit without becoming reckless.
A reversible move should create information: a sketch should reveal structure, a candidate interpretation should be tested, and a parked question should preserve state. Reversibility is useful only when it reduces uncertainty or protects future options.
61. reject a root
For reject a root, classify the move as cheaply reversible, moderately costly to reverse, or effectively irreversible under examination time. Then name the information or time that would be lost if the decision proved wrong.
For practice, compare two routes: one that preserves options and one that commits early. Identify the evidence threshold that should trigger commitment. This trains learners to explore without becoming indecisive and to commit without becoming reckless.
A reversible move should create information: a sketch should reveal structure, a candidate interpretation should be tested, and a parked question should preserve state. Reversibility is useful only when it reduces uncertainty or protects future options.
62. accept a root
For accept a root, classify the move as cheaply reversible, moderately costly to reverse, or effectively irreversible under examination time. Then name the information or time that would be lost if the decision proved wrong.
For practice, compare two routes: one that preserves options and one that commits early. Identify the evidence threshold that should trigger commitment. This trains learners to explore without becoming indecisive and to commit without becoming reckless.
A reversible move should create information: a sketch should reveal structure, a candidate interpretation should be tested, and a parked question should preserve state. Reversibility is useful only when it reduces uncertainty or protects future options.
63. stop checking
For stop checking, classify the move as cheaply reversible, moderately costly to reverse, or effectively irreversible under examination time. Then name the information or time that would be lost if the decision proved wrong.
For practice, compare two routes: one that preserves options and one that commits early. Identify the evidence threshold that should trigger commitment. This trains learners to explore without becoming indecisive and to commit without becoming reckless.
A reversible move should create information: a sketch should reveal structure, a candidate interpretation should be tested, and a parked question should preserve state. Reversibility is useful only when it reduces uncertainty or protects future options.
64. reopen a closed answer
For reopen a closed answer, classify the move as cheaply reversible, moderately costly to reverse, or effectively irreversible under examination time. Then name the information or time that would be lost if the decision proved wrong.
For practice, compare two routes: one that preserves options and one that commits early. Identify the evidence threshold that should trigger commitment. This trains learners to explore without becoming indecisive and to commit without becoming reckless.
A reversible move should create information: a sketch should reveal structure, a candidate interpretation should be tested, and a parked question should preserve state. Reversibility is useful only when it reduces uncertainty or protects future options.
65. recalculate verified work
For recalculate verified work, classify the move as cheaply reversible, moderately costly to reverse, or effectively irreversible under examination time. Then name the information or time that would be lost if the decision proved wrong.
For practice, compare two routes: one that preserves options and one that commits early. Identify the evidence threshold that should trigger commitment. This trains learners to explore without becoming indecisive and to commit without becoming reckless.
A reversible move should create information: a sketch should reveal structure, a candidate interpretation should be tested, and a parked question should preserve state. Reversibility is useful only when it reduces uncertainty or protects future options.
66. commit scarce time
For commit scarce time, classify the move as cheaply reversible, moderately costly to reverse, or effectively irreversible under examination time. Then name the information or time that would be lost if the decision proved wrong.
For practice, compare two routes: one that preserves options and one that commits early. Identify the evidence threshold that should trigger commitment. This trains learners to explore without becoming indecisive and to commit without becoming reckless.
A reversible move should create information: a sketch should reveal structure, a candidate interpretation should be tested, and a parked question should preserve state. Reversibility is useful only when it reduces uncertainty or protects future options.
67. leave a blank
For leave a blank, classify the move as cheaply reversible, moderately costly to reverse, or effectively irreversible under examination time. Then name the information or time that would be lost if the decision proved wrong.
For practice, compare two routes: one that preserves options and one that commits early. Identify the evidence threshold that should trigger commitment. This trains learners to explore without becoming indecisive and to commit without becoming reckless.
A reversible move should create information: a sketch should reveal structure, a candidate interpretation should be tested, and a parked question should preserve state. Reversibility is useful only when it reduces uncertainty or protects future options.
68. write an extra risky point
For write an extra risky point, classify the move as cheaply reversible, moderately costly to reverse, or effectively irreversible under examination time. Then name the information or time that would be lost if the decision proved wrong.
For practice, compare two routes: one that preserves options and one that commits early. Identify the evidence threshold that should trigger commitment. This trains learners to explore without becoming indecisive and to commit without becoming reckless.
A reversible move should create information: a sketch should reveal structure, a candidate interpretation should be tested, and a parked question should preserve state. Reversibility is useful only when it reduces uncertainty or protects future options.
69. add unsupported explanation
For add unsupported explanation, classify the move as cheaply reversible, moderately costly to reverse, or effectively irreversible under examination time. Then name the information or time that would be lost if the decision proved wrong.
For practice, compare two routes: one that preserves options and one that commits early. Identify the evidence threshold that should trigger commitment. This trains learners to explore without becoming indecisive and to commit without becoming reckless.
A reversible move should create information: a sketch should reveal structure, a candidate interpretation should be tested, and a parked question should preserve state. Reversibility is useful only when it reduces uncertainty or protects future options.
70. remove an exception
For remove an exception, classify the move as cheaply reversible, moderately costly to reverse, or effectively irreversible under examination time. Then name the information or time that would be lost if the decision proved wrong.
For practice, compare two routes: one that preserves options and one that commits early. Identify the evidence threshold that should trigger commitment. This trains learners to explore without becoming indecisive and to commit without becoming reckless.
A reversible move should create information: a sketch should reveal structure, a candidate interpretation should be tested, and a parked question should preserve state. Reversibility is useful only when it reduces uncertainty or protects future options.
71. ignore a constraint
For ignore a constraint, classify the move as cheaply reversible, moderately costly to reverse, or effectively irreversible under examination time. Then name the information or time that would be lost if the decision proved wrong.
For practice, compare two routes: one that preserves options and one that commits early. Identify the evidence threshold that should trigger commitment. This trains learners to explore without becoming indecisive and to commit without becoming reckless.
A reversible move should create information: a sketch should reveal structure, a candidate interpretation should be tested, and a parked question should preserve state. Reversibility is useful only when it reduces uncertainty or protects future options.
72. submit ambiguous handwriting
For submit ambiguous handwriting, classify the move as cheaply reversible, moderately costly to reverse, or effectively irreversible under examination time. Then name the information or time that would be lost if the decision proved wrong.
For practice, compare two routes: one that preserves options and one that commits early. Identify the evidence threshold that should trigger commitment. This trains learners to explore without becoming indecisive and to commit without becoming reckless.
A reversible move should create information: a sketch should reveal structure, a candidate interpretation should be tested, and a parked question should preserve state. Reversibility is useful only when it reduces uncertainty or protects future options.
73. finalise source ownership
For finalise source ownership, classify the move as cheaply reversible, moderately costly to reverse, or effectively irreversible under examination time. Then name the information or time that would be lost if the decision proved wrong.
For practice, compare two routes: one that preserves options and one that commits early. Identify the evidence threshold that should trigger commitment. This trains learners to explore without becoming indecisive and to commit without becoming reckless.
A reversible move should create information: a sketch should reveal structure, a candidate interpretation should be tested, and a parked question should preserve state. Reversibility is useful only when it reduces uncertainty or protects future options.
74. finalise units
For finalise units, classify the move as cheaply reversible, moderately costly to reverse, or effectively irreversible under examination time. Then name the information or time that would be lost if the decision proved wrong.
For practice, compare two routes: one that preserves options and one that commits early. Identify the evidence threshold that should trigger commitment. This trains learners to explore without becoming indecisive and to commit without becoming reckless.
A reversible move should create information: a sketch should reveal structure, a candidate interpretation should be tested, and a parked question should preserve state. Reversibility is useful only when it reduces uncertainty or protects future options.
75. finalise accuracy
For finalise accuracy, classify the move as cheaply reversible, moderately costly to reverse, or effectively irreversible under examination time. Then name the information or time that would be lost if the decision proved wrong.
For practice, compare two routes: one that preserves options and one that commits early. Identify the evidence threshold that should trigger commitment. This trains learners to explore without becoming indecisive and to commit without becoming reckless.
A reversible move should create information: a sketch should reveal structure, a candidate interpretation should be tested, and a parked question should preserve state. Reversibility is useful only when it reduces uncertainty or protects future options.
76. finalise question number
For finalise question number, classify the move as cheaply reversible, moderately costly to reverse, or effectively irreversible under examination time. Then name the information or time that would be lost if the decision proved wrong.
For practice, compare two routes: one that preserves options and one that commits early. Identify the evidence threshold that should trigger commitment. This trains learners to explore without becoming indecisive and to commit without becoming reckless.
A reversible move should create information: a sketch should reveal structure, a candidate interpretation should be tested, and a parked question should preserve state. Reversibility is useful only when it reduces uncertainty or protects future options.
77. finalise word-limited summary
For finalise word-limited summary, classify the move as cheaply reversible, moderately costly to reverse, or effectively irreversible under examination time. Then name the information or time that would be lost if the decision proved wrong.
For practice, compare two routes: one that preserves options and one that commits early. Identify the evidence threshold that should trigger commitment. This trains learners to explore without becoming indecisive and to commit without becoming reckless.
A reversible move should create information: a sketch should reveal structure, a candidate interpretation should be tested, and a parked question should preserve state. Reversibility is useful only when it reduces uncertainty or protects future options.
78. finalise optional choice
For finalise optional choice, classify the move as cheaply reversible, moderately costly to reverse, or effectively irreversible under examination time. Then name the information or time that would be lost if the decision proved wrong.
For practice, compare two routes: one that preserves options and one that commits early. Identify the evidence threshold that should trigger commitment. This trains learners to explore without becoming indecisive and to commit without becoming reckless.
A reversible move should create information: a sketch should reveal structure, a candidate interpretation should be tested, and a parked question should preserve state. Reversibility is useful only when it reduces uncertainty or protects future options.
79. reversible-move final rule
For reversible-move final rule, classify the move as cheaply reversible, moderately costly to reverse, or effectively irreversible under examination time. Then name the information or time that would be lost if the decision proved wrong.
For practice, compare two routes: one that preserves options and one that commits early. Identify the evidence threshold that should trigger commitment. This trains learners to explore without becoming indecisive and to commit without becoming reckless.
A reversible move should create information: a sketch should reveal structure, a candidate interpretation should be tested, and a parked question should preserve state. Reversibility is useful only when it reduces uncertainty or protects future options.
Irreversible moves deserve stronger checks
The more costly a move is to undo, the more verification it deserves beforehand. Rounding early, deleting a valid case, choosing the wrong optional question or spending a large block of time can damage later work even if the local reasoning is reasonable.
Links
Use the Examination Craft hub, Vol 0124 Constraint Stack, the relevant English, Mathematics and Science hubs, and the PSLE Learner’s Guide.
Official-source discipline
For the 2027 SEC G2 school-candidate framework, use the current SEAB G2 syllabus directory and linked subject syllabuses. Reversibility control is an eduKateSengkang examination framework, not an SEAB marking label.
Final rule
Explore cheaply while uncertainty is high. Commit when the evidence is strong enough. The harder a decision is to undo, the more carefully you should verify it before letting later work depend on it.
