Learners will analyse particle theory in relation to substances in…

Hot and Cold: Particles on the Move Grade 6

Why tires go soft in winter, why sidewalks have gaps, and how a thermometer knows. Five lessons on what heating and cooling do to the particles in everything around us.

• Why do bike tires go soft in winter? 45–60 min

  Students stretch a balloon over a bottle, move it between warm and ice water, and find out what happens to air particles when they cool down. Then they explain a cyclist's 'flat' tire on the first cold morning.

• Why does food colouring spread faster in hot water? 45–60 min

  Two cups, two drops, one race. Students drop food colouring into warm and ice-cold water at the same moment, then explain what the moving colour tells us about particles they can't see.

• How does a thermometer know? 50–60 min

  Teams build a working thermometer from a bottle of coloured water and a clear straw, then calibrate it against a real thermometer. At the end, they explain how any liquid thermometer 'knows' the temperature.

• Why do sidewalks have cracks on purpose? 50–60 min

  Students loosen a stuck jar lid with warm water, then go on a gap hunt around the school to find and measure the joints engineers build into sidewalks, walls and railings. They explain why solid things need room to grow and shrink.

• Can you keep an ice cube frozen the longest? 60 min, plus a 40-minute wait (teach something else while the ice sits)

  A design challenge with insulation, a budget and a class leaderboard. Teams build an ice cube keeper, measure how much melted, and explain why the best designs slow down heat moving in.