Category: Science
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PSLE Science Reality Lab Vol No.424 | “N95” — Does 95 Mean It Blocks 95% of Every Airborne Particle in Every Use?
A massive Primary 5/6 evidence guide to the N95 marking: how to separate a NIOSH particulate filter-class test criterion from a universal guarantee about every particle, contaminant, face fit or real-world use.
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PSLE Science Reality Lab Vol No.423 | “4-Tick WELS Washing Machine” — Does Four Ticks Mean It Uses One Quarter as Much Water?
A massive Primary 5/6 evidence guide to Singapore’s WELS label: why four water-efficiency ticks are a category-specific grade under stated test conditions, not a literal promise that a washing machine uses one quarter as much water in every home.
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PSLE Science Reality Lab Vol No.422 | “Sample Rate = 1 Reading/s” — Can the Sensor Track Every One-Second Change?
A massive Primary 5/6 evidence guide to sensor datasheets: why one reading per second tells you how often values are produced, not how quickly the physical sensor can follow a changing quantity.
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PSLE Science Reality Lab Vol No.421 | “Accuracy = ±2% RH at 23°C” — Does That Same Accuracy Claim Apply at Every Temperature?
A massive Primary 5/6 evidence guide to instrument specifications: why an accuracy statement tied to 23°C or another test condition should not be silently extended to every operating condition.
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PSLE Science Reality Lab Vol No.420 | “Aboveground Biomass = 150 Mg/ha” — Did Scientists Cut Down and Weigh Every Tree?
A massive Primary 5/6 evidence guide to forest biomass maps: how field observations, lidar measurements, sampling and models can produce biomass estimates without weighing every tree in every mapped area.
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PSLE Science Reality Lab Vol No.419 | “River Discharge = 120 m³/s at 06:00” — Was 120 m³/s Directly Measured at That Exact Moment?
A massive Primary 5/6 evidence guide to river-discharge dashboards: why a value shown at one timestamp may be estimated from continuously measured stage and a site-specific rating curve rather than directly measured at that exact moment.
