4. Convection in a Pan - Getting Ready
Test the hot air balloon demo
- Use cellophane tape to seal the top seam and any holes in the dry cleaner bag. Use as little tape as possible.
- Clip 3-4 paper clips around the bottom edge of the bag, as evenly distributed as possible. This will keep the bag upright and stable as it takes flight.
- Hold the bag at the top. Get helpers or use 2 chairs to keep the bottom edges open.
- Turn the blow dryer on at the lowest setting and hold it near the bottom of the bag (but not so close that the bag begins to melt). Allow the hot air to inflate the bag.
- When the bag is fully inflated, let go of it to test its buoyancy. If it lifts off, let it go. If it doesn’t, continue filling with the blow dryer for a little longer.
- Watch its flight, taking note of how stable it is in the air. When it lands again, adjust the paper clips to make it more stable. If it tilts one way, move them to different locations. If it flips over completely, add more paper clips. If it doesn't fly at all, remove some clips.
Set up the pie pans
- Make copies of the Convection in a Pan student handout.
- Each pie pan will need about 2-3 cups of water. In a large pitcher or bucket, fill the bucket with as much water as you need for all the groups (plus a few cups extra).
- The dilution of soap to water is approximately 1 tablespoon soap to 1 cup water. Add the appropriate amount of soap to the water.
- Mix the soap into the water gently, trying to minimize the number of bubbles. The final solution should be very fluid and should leave swirly trails as you move your spoon or hand through the solution.
- Set the materials for each group into a pie pan: candle, 4 film canisters, matches, food coloring droppers.