Sample lesson, pilot version. A practising Alberta teacher will review this lesson and pilot teachers will teach it in January 2027. Tell us what works and what doesn’t.
1. Mission (5 min)
Read this to the class:
On the first cold morning in November, a Grade 6 student in Red Deer went to ride her bike to school. Both tires felt soft. Nobody had touched them, and there were no holes. Your team’s job: find out where the air went.
Give each team a mission card with the question written on it. Teams of three, with three jobs that rotate: Lead (handles the bottle), Timer (watches the clock), Recorder (writes and draws).
2. Bet (5–10 min)
Show a bottle with a balloon stretched over its mouth. Ask:
- What will happen to the balloon if we stand the bottle in warm water?
- What about ice water?
Every student writes a prediction and one reason why on their sheet. Then they draw what they think the air inside the bottle looks like up close, as tiny dots.
3. Hunt (20 min)
- Stand the empty, open bottle in the ice water tub for two minutes so the air inside gets cold.
- Stretch the balloon over the mouth while the bottle is still in the ice water. Make sure it’s on tight.
- Move the bottle to the warm tub for two minutes. The Recorder notes what the balloon does every 30 seconds.
- Move it back to the ice water for two minutes. Record again.
- Each team repeats warm, then cold, once more, so they can trust their result.
Teacher note: going from ice water to warm water gives the biggest change. Even so, the balloon usually lifts and fills out partway rather than inflating fully. A small change that happens every time is exactly the right result, and a good chance to talk about how scientists notice small effects.
Fair-test moment: ask the class what they kept the same each time (the bottle, the balloon, the time in each tub) and what they changed (the water temperature). That’s what makes it a fair test.
4. Reveal (10–15 min)
Collect what every team saw on the board. Most teams will see the balloon lift and fill out in warm water and droop again in ice water.
Then the key question: did any air get into or out of the bottle? No. The balloon sealed it. It’s the same air the whole time.
Explain with particles:
- Air is made of tiny particles that are always moving.
- When the air warms up, the particles move faster and push harder on the walls of the bottle and the balloon. The balloon fills up.
- When the air cools down, the particles slow down and push less. The balloon droops.
- The particles don’t shrink or disappear. They move more slowly.
Back to the bike: the air in the tires didn’t suddenly leak out. It got cold, the particles slowed down and pushed less, so the tires felt soft. (Tires do lose a little air slowly through the rubber over weeks, which is another reason to check them, but that sudden softness on the first cold morning is mostly the cold.)
Common mix-ups to listen for:
- “Cold air got in.” No air got in or out.
- “The particles got smaller.” They stay the same size. They move less.
- “Cold sucks the balloon in.” Nothing pulls. Warm particles push more, cold particles push less.
5. Act (10 min)
Each student writes a short note to the cyclist, in three sentences or fewer:
- What happened to your tires.
- Why it happened, using the word particles.
- What you should do about it.
Good answers mention checking tire pressure when the weather turns cold.
Exit ticket: draw the particles in a warm bottle and a cold bottle, side by side.
Background for the teacher
Gases expand when heated and contract when cooled. In a closed container that can’t stretch, like a tire, the pressure rises and falls instead. That’s why car and bike tires lose pressure as the weather cools, and why drivers are told to check their tires in the fall.
Assessment
| Looks for | Not yet | Getting there | Got it |
|---|---|---|---|
| Describes what happened | Describes the balloon only | Links balloon change to water temperature | Links the change to heating and cooling of the air inside |
| Explains with particles | No particles | Particles mentioned, but they “shrink” or “escape” | Particles move faster when warm and slower when cold, and push more or less |
| Applies it | No link to the bike | Links to the bike without a reason | Explains the soft tire with particles and suggests checking pressure |