In the kit there are some ceramic tiles of different
colors. Suppose that you want to warm them up.
The tiles all start out at room temperature, so that the higher
temperature thermal sensing sheet lying on a tile is black or brown.
Here are some ways to warm the tile:
hold it in your closed hand
rub it rapidly on fabric (think of a way to hold it without
letting your hand come in contact with it)
place a container of hot water on it
put it over a heat vent or radiator
place it in sunshine
rest it on an electrical device that is turned on, like a computer
perhaps you can think of another way --
For each method, estimate how long you thing it will take to cause a
change that is easily detected by the thermal sensing sheet -- to turn it
green, for example. Then try it, and record what color actually resulted.