YEARS K–6 IDEAS
ARTICLES
FOR THE CLASSROOM
Three Possible STEM Lessons for K-6 Teachers to Use (continued)
Preparation
Lesson steps
Review what the students know about heating and cooling substances such as chocolate.
Explain that this activity will examine what happens to a gas when heat energy is removed (it is cooled).
Students form groups of 3 or 4. Each group is given a balloon. They are to inflate the balloon and tie it off.
Students are given a number of objects and are asked to measure the diameter of the balloon. The objects they
can choose from include a 30 cm ruler, some string/cotton, a 20-cent piece, a wooden skewer and a black marker.
Teachers may have to explain what ‘the diameter’ is.
Students discuss how best to measure the diameter using the equipment provided. They also decide on the units
they will use to be as accurate as possible. If they wish, they could use more than one method, and discuss the
merits of each method at the end.
Students measure the diameter of the inflated balloon and record their measurement.
Students mark their balloons so they know which one is theirs. The balloons are then placed into the freezer or
refrigerator overnight. Ask all the students to predict what will happen to the balloon.
Remove the balloons from the freezer/refrigerator. Students then examine their balloon and measure its diameter
again, using the same method(s) used previously.
Students discuss their results. Were their predictions correct? Did anything about the balloon change when heat
energy was removed?
Ask students to make a general statement about how removing heat affects air. The balloon’s diameter should
be less straight after removing it from the freezer. Removing heat removes energy, so the air particles have less
energy, meaning they move more slowly. Therefore they do not push on the balloon’s surface as much (they exert
less pressure) so the balloon has a smaller diameter than before.
Students could dramatise the movement of air particles in the balloon. Students move around quickly in a confined
area. They take up the space within the area. When they are cooled by removing the heat energy, the particles
(students) slow down. They still move around, but not as quickly, and take up less space than before.
Ask the students about the methods they used to measure the diameter of the balloon. Discuss the following
questions: Which one did they use and why? Which units did they use and why? What could they have done so
their measurements were more accurate?
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SCIENCE EDUCATIONAL NEWS VOL 67 NO 4