Fill one flat-sided plastic bottle with warm water, and leave the other filled with air. Tape two small strips of the thermal sensing sheet to one face of the air-filled bottle, with one piece facing in and the other facing out (so that you can tell the temperature of this face from either direction). There are two ways to stack these: with the warm water on the top, or the warm water on the bottom. Which way moves the thermal energy across the air-filled container the fastest? See for yourself!

The picture shows the setup. The bottles are resting on lengths of straw, to keep them from touching the table (when we turn the stack of bottles over, we are changing which side is on the bottom. We don't want to also change which side is touching the table, because that would be a different experiment).

After observing a stack for 4 minutes, empty and refill the warm water bottle, and give the air bottle a chance to return to room temperature.

Check the box when you are done:  
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