Thermal Expansion
Thermal Expansion is when things get bigger because they are heated up.
A small metal lid sits tight on a glass jar and will not turn. You hold the lid under hot running water for a few seconds. The metal heats up and its tiny parts spread apart, making the lid just a bit wider. Now the lid turns with ease — it grew from the heat and no longer grips the jar as tight.
Explaining thermal expansion by grade level
Put a balloon over a bottle and set the bottle in warm water. The balloon starts to puff up. The air inside the bottle gets warm. Warm air takes up more room, so it pushes into the balloon.
Projects that explore thermal expansion
Thermal expansion means things get bigger when heated, and different gases expand by different amounts. Five gases sealed in Mylar balloons grow in volume as the water around them rises from 1 degrees C to 60 degrees C. Oxygen expanded the most with a 36.5% volume increase, while carbon dioxide expanded the least at 15.3%.
Glass sheets brought to five temperatures from 0 to 100 degrees Celsius get bigger or smaller as the heat changes. This project tests whether those size changes affect what happens when a metal ball drops through a PVC pipe onto each sheet: does the glass stay whole, or shatter into many pieces?