Work in Progress
Please pardon our progress while we refine the look and functionality of our new ALEX site! You can still access the old ALEX site at If you would like to share feedback or have a question for the ALEX Team, you can use the contact form here, or email us directly at

Learning Resource Type

Classroom Resource

Heating and Cooling | Hero Elementary

Subject Area





In these Hero Elementary activities, children explore how materials change when heated and cooled. For example, if you cool a liquid, it may become solid. What happens when you reverse the process and heat the solid—does it become liquid again? Or, if you heat a solid, it may become liquid. If you cool the liquid, will it get solid again? Children will discover that some changes are reversible and others are not. You can heat ice and it becomes liquid water. If you cool the water, it freezes and becomes ice again. If you heat popcorn, it pops and it does not “unpop” if you cool it. There is no way to unpop popcorn.

    Science (2015) Grade(s): 2


    Provide evidence that some changes in matter caused by heating or cooling can be reversed (e.g., heating or freezing of water) and some changes are irreversible (e.g., baking a cake, boiling an egg).

    Unpacked Content



    • Properties
    • Evidence
    • Change
    • Matter
    • Heating
    • Cooling
    • Reversible
    • Irreversible


    Students know:
    • Characteristics of materials before heating or cooling.
    • Characteristics of materials after heating and cooling.
    • Characteristics of materials when heating or cooling is reversed.


    Students are able to:
    • Analyze evidence to support a claim that heating and cooling causes change in matter.


    Students understand that:
    • Heating or cooling a substance may cause changes that can be observed. Sometimes these changes are reversible and sometimes they are not.

    Scientific and Engineering Practices

    Engaging in Argument from Evidence

    Crosscutting Concepts

    Cause and Effect
    Link to Resource

    CR Resource Type

    Learning Activity

    Resource Provider


    License Type