Level 1 of 4Speed detective
Watch the motion
Temperature
Cool
slowerfaster
Level 1 · Look closely
Speed detective
Particles are always moving. Compare two samples and use their motion to spot the warmer one.
Particle scientist
You cracked evaporation!
Heating makes particles move faster. The fastest can leave the surface as vapor — they do not disappear.
Make a prediction
Which sample is warmer?
Use the length of the motion trails as evidence.