When Hot Is Not

Graphic for When Hot Is Not Science Recipe

Why does a 55-degree day in summer feel cold, while a 55-degree day in winter feels warm? In this activity, you will experience a temperature change and discover that “hot” and “cold” are relative terms.

Age: 6+ 
Time: 10 minutes
Topics: temperature, senses, perception

What You Need

  • 3 bowls 
  • Tape 
  • Markers 
  • Water
  • Ice
  • Clock or timer

What To Do

1. Think about some weather that feels hot to you – would it feel as hot to someone who lives in a tropical place? Think about some weather that feels cold to you – would it feel as cold to someone who lives in the Arctic regions? Talk about why “hot” and “cold” are often hot or cold only when compared to something else.  

2. Using your three bowls, the tape, and the marker, label one bowl “cold.” Label another “warm.” Leave the third un-labeled. 

3. Fill the bowl marked “cold” with ice water. Fill the bowl marked “warm” with warm tap water. Fill the un-marked bowl with water at room temperature. 

4. Place one hand in the bowl marked “cold” and the other in the bowl marked “warm” for one minute. (This can feel like a long time to wait without moving, so try counting to sixty, singing a song, or looking out the window to pass the time.)

5. Next, quickly place both hands in the unmarked bowl at the same time. Does the water feel warm or cold to your left hand? To your right hand? Why do you think that? 

6. Things to think or talk about:

  • What do you think would happen if you used the bowls in a different order, such as starting with one hand in the cold bowl and one hand in the room temperature bowl, and then moving them both to the warm water? Try it and find out! 
  • Can you think of other times when you felt temperatures that were surprising or seemed to change? Someone’s fingers that felt cold to your face but warm to your hand? Bath water that felt too hot at first but not so bad once you’d been in it for a minute? How do you think those experiences are similar to or different from this experiment?

What’s Happening?

One of the main ways your brain interprets temperature sensations is by comparing changes in temperature: how much hotter or colder does this feel now than it did before? When you move your hand from the cold water to the (warmer) room temperature water, your hand senses that the temperature has gone up and your brain interprets it as “warm”. As you move your other hand from the warm water to the (colder) room temperature water, the hand senses that the temperature has gone down, so your brain interprets it as “cold”. Although both hands are actually experiencing the same temperature, your brain interprets it differently for each hand, based on how it compares to what each hand sensed before. The greater the difference in temperature is between the different bowls of water, the easier it will be to sense a difference.