Make a Homemade Thermometer

Are you looking for a quick and fun activity that also teaches you something about chemistry? Well, here it is! The video above demonstrates how to make your very own thermometer with just a few simple supplies. Enjoy!


Materials Required

Empty glass bottle (but plastic would work, too)

Food coloring

Modeling clay

Clear straw

½ cup rubbing alcohol

½ cup of water

Funnel (optional but helpful)

Permanent marker (optional)

Metric ruler (optional)

Adult supervision (NOT optional – Do not attempt this experiment without an adult)

*This activity is best completed in a well-ventilated room so the fumes from the rubbing alcohol do not make you dizzy or sick.



  1. Start by pouring the ½ cup of water to your empty bottle, using the funnel if necessary.
  2. Next, add the ½ cup of rubbing alcohol to the bottle, again using the funnel.
  3. Add a few drops of food coloring to the bottle and gently mix it all together by swishing the bottle. Do not shake the bottle too hard or your mixture could splash out and make a mess.
  4. Optional step:Using the metric ruler and permanent marker, start at the top of the straw and mark it at ½ centimeter intervals. Leave the bottom 4-5 centimeters unmarked as this part of the straw will be inserted into the liquid in your bottle. These marks are optional, but could be helpful in determining how much the liquid expands and contracts in different temperatures.
  5. Insert your straw (unmarked side down if you followed step 4) into the bottle but make sure it does not fall all the way to the bottom. Instead, make sure it stays suspended no more than half-way into the liquid.
  6. Using your modeling clay, create a seal aroundthe straw at the mouth of the bottle. The straw opening should not be blocked, only the space between the bottle and the straw should be sealed.
  7. That’s it! You are ready to test your thermometer! Move it to different placed around and inside your house to see what happens. Try placing it in the sun, in the fridge, near a heater or air conditioning vent, and watch the magic.



When the liquid in the bottle gets warmer it expands. Since the clay seals the bottle but leaves the straw unsealed, the liquid expands upwards within the straw. On the other hand, when the liquid gets cold it contracts, or moves back down the straw.