Category: Science

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A massive Primary 5/6 PSLE Science Reality Lab guide to insulation R-values: learn why R-4 is a thermal-resistance rating, not a percentage of heat blocked or a guarantee of four-times energy savings, and how to compare insulation claims fairly.

PSLE Science Reality Lab Vol No.199 | “BOD₅ = 5 mg/L” — Does That Mean There Are 5 mg/L of Bacteria in the Water?

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A massive Primary 5/6 PSLE Science Reality Lab guide to biochemical oxygen demand: learn why BOD₅ in mg/L reports oxygen used during a specified test, not the mass or count of bacteria, and how to evaluate water-quality claims without overreading the number.

PSLE Science Reality Lab Vol No.198 | “Dissolved Oxygen = 80% Saturation” — Is 80% of the Water Oxygen?

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A massive Primary 5/6 PSLE Science Reality Lab guide to dissolved-oxygen percent saturation: learn why 80% saturation does not mean 80% of water is oxygen, why temperature, pressure and salinity matter, and how to keep water-quality claims inside the evidence.

PSLE Science Reality Lab Vol No.197 | “Water Activity = 0.85” — Is the Food 85% Water?

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A massive Primary 5/6 PSLE Science Reality Lab guide to water activity: learn why aw = 0.85 is not 85% water by mass, how it differs from moisture content, and how to interpret the measurement without turning it into food-safety advice.

PSLE Science Reality Lab Vol No.196 | “100 CFU/mL” — Does That Mean Exactly 100 Microbial Cells in Every Millilitre?

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A massive Primary 5/6 PSLE Science Reality Lab guide to colony-forming units: learn why 100 CFU/mL is a culture-based estimate, not automatically an exact count of 100 individual microbial cells in every millilitre.

PSLE Science Reality Lab Vol No.195 | “Energy Use = 350 kWh/year” — Will Every Home Use Exactly 350 kWh?

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