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It’s hot in here

Wooden thermometer close up


Temperature is relative. In winter, you may feel really hot entering the house when you’re coming in from the cold but after sitting in the house for a while, you may start to feel cold. Getting out of a hot shower makes the bathroom feel cold. Playing with this phenomenon is a wonderful way to discover temperature and extend the vocabulary of temperature, no matter the season.


  • A thermometer.
  • Bowls of cold, warm, and hot water.


Discuss today’s temperature: Is it a hot day or a cold day? Was morning tea hot or cold? If you feel cold, how do you dress? How do you cool down?

Set up a few bowls with cold, warm, and hot water. Remember that prolonged exposure to very cold water can be a problem, so monitor this activity carefully. Let the children dip their hands in cold water (from the cold tap) and then in warmer water. Does it feel really warm now? What about the hotter water?

NOTE: I know using cold, warm, and hot water does not sound dangerous, but be careful with this activity. Ensure that the hot and cold water are not extreme. Tap water is fine. Don’t use ice.

What’s the STEM?

This playful activity is a wonderful way to extend the vocabulary of temperature. The idea that people experience temperature differently and that ‘hotness’ is not fixed is fascinating to children. I would suggest introducing the activity and the fake thermometer. Then, once the children have experienced differing opinions on what is hot and what is not, a conversation about why we need thermometers can take place. This is a good time to introduce real thermometers.

Observations, conclusions and extensions

The aim here is to introduce the thermometer at a point where the numbers mean something and explain why we need accurate measurement of temperature. 

Paper craft themometer

A paper classroom thermometer showing temperature is a nice idea. I made one years ago out of a strip of red ribbon tied to some white ribbon that looped around so you could move the temperature up and down, similar to this version I made out of card (pictured). It helps children understand that when it is hot, the mercury rises, and when it is cold, it lowers. Many children may have never seen a mercury thermometer. What type of thermometer are you using?

The numbers may not mean very much to the children, especially the younger children, but the observation that warm water (or weather) makes the mercury rise and that cold water makes it fall may help explain the concepts.

NOTE: Be careful with mercury thermometers in an early childhood setting.

STEM language

Use your explorations to introduce this STEM vocabulary to the children: hot, hotter, cold, colder, freezing, cool, warm, boiling, thermometer.

Hayley Bates
Article author: Hayley Bates
National Certifications Coordinator

This passionate mathematician and former science teacher will inspire you with her enthusiasm for inquiry-based learning and her determination to provide high-quality hands-on and fun professional development.

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