🧪 Science with Sarah: Topo-Chico Thermometers! 🌡️

A bit of science will transform the glass bottle into a homemade thermometer

A bit of science will transform the glass bottle into a homemade thermometer.

👉 Watch the video of Sarah’s school science experiment here!

Hello parents, teachers and students! Want to see the science of meteorology right in your home? Try making this Topo-Chico thermometer with Meteorologist Sarah Spivey and her awesome assistant, David Sears!

Be sure to check out GMSA@9 on Wednesdays when Meteorologist Sarah Spivey does the demonstrations and explains the science behind it.

Science with Sarah: Invite KSAT to your school for live science experiments. (KSAT)


Here's how to make a Topo-Chico thermometer! (Copyright KSAT 2022 - All rights reserved)
  • A Topo-Chico glass bottle (or really, any glass bottle will work)
  • Modeling clay
  • A clear straw
  • Rubbing alcohol (USE ADULT SUPERVISION)
  • Water
  • Food dye


  • STEP 1: Take the empty glass bottle and fill it 1/3 of the way up with water. Then add rubbing alcohol until 2/3 of the bottle is filled. Because this experiment contains alcohol, please use adult supervision when doing this experiment.
  • STEP 2: Add a few drops of food coloring to the alcohol/water mixture
  • STEP 3: Using modeling clay, secure the straw to the top of the bottle. Make sure that the bottom of the straw is NOT touching the bottom of the bottle and that the top of the straw is NOT covered. It should look like this! ⬇️
This is what your Topo-Chico thermometer should look like! (Copyright KSAT 2022 - All rights reserved)
  • STEP 4: To test your thermometer, place it outside and in the sunlight. You should see that the alcohol/water mixture gradually rises in the straw as the temperature increases. When you bring it back inside, you should see the level in the straw gradually fall as the bottle cools down.
  • TRY THIS: To quickly test your thermometer, place the glass bottle in a warm water bath or an ice bath and watch the thermometer rise or fall quickly!


This is a good example of heat contraction and expansion! When the liquid gets hot, it expands. This causes the pressure of the air inside the bottle to increase. The air pushes on the liquid, and the liquid has nowhere to go but up the straw! If you find that your thermometer is not working properly, check to make sure the modeling clay seal is very tight.


If you’d like Sarah and David to come to your school and conduct a science experiment live on KSAT, email sciencewithsarah@ksat.com.

Parents and guardians: upload a video of your child performing the activity by clicking here. Send it in and you might see it on GMSA @ 9 a.m.!

About the Authors:

Sarah Spivey is a San Antonio native who grew up watching KSAT. She has been a proud member of the KSAT Weather Authority Team since 2017. Sarah is a Clark High School and Texas A&M University graduate. She previously worked at KTEN News. When Sarah is not busy forecasting, she enjoys hanging out with her husband and cat, and playing music.

Ben Spicer is a digital journalist who works the early morning shift for KSAT.