Make a Homemade Thermometer!

Your middle schooler will be learning all about heat energy and temperature measurement and will likely get to use a lab thermometer. This project will enable your child to construct a homemade thermometer that will compliment what they are learning about this instrument in school.

What You Need:

Tap water

Rubbing alcohol

11-ounce clear, narrow-necked plastic bottle

Red food coloring

Clear plastic drinking straw

Modeling clay

What You Do:

Step 1

Add equal parts of tap water and rubbing alcohol to the bottle, filling it to about 1/8 to a 1/4 of the bottle.

Step 2

Add a couple of drops of red food coloring and mix by shaking the bottle.

Step 3

Put the straw in the bottle, but don't let the straw touch the bottom.

Step 4

Use the modeling clay to seal the neck of the bottle, so the straw stays in place.

Step 5

To test if the homemade thermometer works have your child place their hands around the bottle and observe what happens to the mixture in the bottle.

Just like any thermometer, the mixture expands when it’s heated. As the alcohol-water mixture expands it moves up through the straw. If the bottle were to get very hot, the liquid would have come through the top of the straw. As an extension, make a scale for the thermometer, you will need to buy a real thermometer and placed it near the homemade one. Using a pen, note the temperature and write its value on a cardboard sheet adjacent to the straw. Repeat this procedure for every 10 to 20 degrees of temperature change.