Education and
Public Engagement
at the Lunar and Planetary Institute
Explore Earth's Climate

Simple Thermometer


Children ages 8 to 13 construct a thermometer and use it to observe temperature changes, in this 15 minute activity.

What's the Point?


For Each Group of 10–15 Children

Supporting Media

Consider setting up a digital media player (such as a computer), speakers, and access to the Internet to display websites or multimedia before, during, or after the activity. 



  1. Share ideas and knowledge.
    • Introduce yourself and the library. Help the children learn each other’s names (if they don’t already).
    • Frame the activity with the main message:  Changes to distant oceans, air moving freely around our globe, and all living things have an influence on our regional environment.
    • Invite the children to talk about what they already know about weather, their direct experiences with it, and their ideas about what features of weather can be measured.  Use open-ended questions and invite the children to talk with you and each other.

    Weather is the conditions of the atmosphere at a given place and time. It changes daily and with the seasons.

    Meteorologists collect measurements at Earth's surface at weather stations or on ships or weather buoys. They typically collect temperature, wind direction and speed, precipitation, humidity, and pressure measurements using the corresponding instruments: thermometers, anemometer, rain gauge, hygrometer, and barometer, respectively. Meteorologists also need to understand what's happening at higher altitudes in order to make weather forecasts. Weather balloons and aircraft (which are equipped with sampling and measuring instruments) gather data from aloft. Meteorologists use satellites to collect data about the atmosphere, including measurements of temperature, cloud cover, and winds, from space.

    Information from many instruments is used to create the computer models that integrate data into a dynamic picture of Earth's weather. High-speed computers make calculations of what the weather is likely to be the coming days, weeks, and years.

  2. Invite the children to build a simple thermometer that they can use at home to monitor changes in temperature. Caution the children that the bottle is NEVER to be used for drinking because it will contain isopropyl alcohol, which should not be inhaled or ingested. Have the children follow these steps:
    • Pour equal parts of water and isopropyl alcohol into the bottle, filling it to about ⅛ to ¼ full.
    • Mix in two drops of food coloring.
    • Suspend the straw in the bottle — without touching the bottom of the bottle — and secure it with Play-Doh or modeling clay around the bottle’s neck. DO NOT DRINK THE LIQUID!
    • Hold the bottle with your hands and observe the changes in the straw.

  3. Heat from the children's hands will warm the thermometer. The air inside the bottle, like the air in a bag of popcorn in the microwave, expands as it gets warm. The increased air pressure makes some of the liquid rise in the straw.


    Left: Thermometer at room temperature
    Right: Thermometer warmed by holding its sides

  4. Discuss how the thermometer works and the limitations — and possibilities — for using their new thermometers at home. Explain that the air inside the bottle, like the air in a bag of popcorn in the microwave, expands as it gets warm. The increased air pressure makes some of the liquid rise in the straw.  Add that while thermometers from the store (which are calibrated to accurately measure temperature) can be used to note the temperature in degrees, their thermometers demonstrate how a thermometer works and responds to warmer temperatures. Invite the children to predict what will happen to the level of the liquid in the straw when they leave, and whether it will be higher in shade or in sunlight.

    Caution that the thermometer is not recommended for use in cold locations. The thermometer works best at room temperatures and at warmer temperatures. It should be stored indoors while the children are using it at home, and only taken outdoors for a few minutes each day to observe temperature changes. Over time, the alcohol will evaporate and the bottle contents will need to be replaced with a new mixture of water, food coloring, and isopropyl alcohol.

    Ask the children to cut the bottle in half (to prevent accidental reuse for drinking) and recycle it when they have completed their extended weather observations at home.

  5. Conclude. Summarize that while it is the nature of weather to be highly variable, the children can keep track of it using their new weather instruments!


Weather Measurements
If desired, expand this station to include other weather tools. Find instructions and materials lists at websites such as:

Build Your Own Weather Station
Includes instructions for building six weather instruments. Appropriate for ages 8 to 13 with adult assistance. 

Be A Citizen Weather Reporter
Instructions and a weather journal data form for recording regular measurements from a weather station’s instruments. Over time, children may be able to observe patterns and trends and use the included tips for making their own weather forecasts.

CoCoRaHS: Community Collaborative Rain, Hail, and Snow Network
Collaborate with others to measure and map precipitation from your registered location. Appropriate for all ages, although children will require adult assistance in getting started.