How to Build a Thermometer

Welcome to a Series of experiments using basic items around the house that help you measure the weather outside your own front door!

Each experiment also includes a quick trick for measuring that part of the atmosphere! Tag me on social media photos and data as you track the weather outside your own front door!


How to Build a Thermometer


What You Need:

  • Water
  • Modeling clay
  • Red food coloring
  • Clear straw
  • Rubbing alcohol
  • Clear plastic bottle (about 12 ounces)

What You Do:

  1. Pour equal amounts of tap water and rubbing alcohol into the bottle until it’s a quarter full.
  2. Add a few drops of red food coloring, and shake the bottle to mix it.
  3. Insert the straw into the bottle, not letting it sink to the bottom.
  4. Wrap modeling clay around part of the straw and the opening of the bottle to make it stay. Let part of the straw stick out of the bottle. The clay should be tight around the straw and cover the bottle mouth, but make sure to leave the top opening of the straw uncovered.

Test the thermometer! Put your hands around the bottle. What happens to the mixture when warm hands are on it?

You can also put the thermometer outside and see how the contraption reacts to the hot or cold temperatures. Or, place the thermometer in a bowl of hot water and then put it immediately in the freezer. What happens?

When the alcohol and water mixture gets hot, the mixture expands, sending the water up the straw. How hot would it have to be for the water to come out of the straw?

Thermometer History: By the way, Galileo invented a rudimentary water thermoscope in 1593, which for the first time, allowed temperature variations to be measured!

Quick Trick Measure: Another trick for estimating temperatures. If where you live you can hear crickets in summertime… Just count the number of chirps in 14 seconds, then add 40 to get the temperature. The number you get will be an approximation of the outside temperature.

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