Alternative and inventive ways of measuring should be encouraged. Encourage group discussions. Because of the use of a hot plate, this activity is for older students. Ask them what makes the hot air rise out of the coffee can. They can change the temperature of the burner and check if it changes the force of the hot air.
Students can passively watch the skies or throw objects into the air and watch what happens.
From these observations you can help facilitate their understanding that the wind is a directional force and that it can be measured. Ask your students what is happening. Encourage discussion about how the hot air is blown into the balloon and how the hot air is kept inside the balloon. Lifting off Students can discuss how the balloon lifts off the ground. Ask them how the pilots stop the balloon from rising.