It’s Just a Phase!

Submitting Organization: Community Resources for Science

Grade: 2nd Grade

Subject Area:  Science

Standards Alignment: Next Generation Science Standards

Physical Science: 2. Structure and Properties of Matter

  • 2-PS1-1. Plan and conduct an investigation to describe and classify different kinds of materials by their observable properties.
  • 2-PS1-4. Construct an argument with evidence that some changes caused by heating or cooling can be reversed and some cannot.

Description of the Activity: Have you ever noticed that you get a little sweaty after exercise or on a hot day? Wonder why your body does that?  Students will explore different liquids and observe them vaporizing into a gas.  Do all liquids vaporize the same?  

  • Students work in pairs. Each partner dabs a small amount of the “green” and “red” liquid on the back of their partner’s hand.
  • Teacher can dab Isopropyl alcohol or antiseptic wipe on back of student hands (optional, but more dramatic for comparison!).

Discussion Questions:

  • Which liquid disappeared the fastest?
  • Which liquid disappeared the slowest?
  • Where did the liquid go?
  • What did the liquid turn into? (Teacher can guide the students to the idea of air, and introduce the vocabulary words “gas” and “vaporize”)
  • What does vaporization feel like on your hand?
  • Does your hand feel cold?  

After students discuss, and consider reasons for why their hand feels cold as the liquid vaporizes, teacher can ask questions to help students understand their hands feel cold because because the liquid is taking energy from your hand (temperature=energy) and using that energy to vaporize the liquid. This is why we sweat! Perspiration on your skin vaporizes, which takes away heat (energy) from your body and cools you off!

Resources Needed:

  • 1 cup or small bowl with water (add a few drops of green food color)
  • 1 cup or small bowl with water + 2 teaspoons salt (add a few drops of red food color)
  • Isopropyl alcohol or antiseptic wipes
  • Cotton balls or Q-tip type swab

Link to further resources: