KOTA Territory Weather School - How to Make a Thermometer at Home
In order to make the thermometer, gather some playdoh or modeling clay, some scotch tape, a marked index card, a clear straw, a clear plastic or glass bottle without any labels on it and some red food coloring.
First, fill the bottle about 80% full with lukewarm water. Add a few drops of red food coloring.
Then, stick the straw about 1/2 to 3/4 down into the bottle, then seal the straw and top of the bottle with playdoh or modeling clay.
Next, tape the index card to the top part of the straw. Use an actual thermometer to get the first reading, and mark the card accordingly.
As the temperature rises and falls, the liquid will expand and contract, indicating what the temperature is as conditions change.