A beaker is placed on a wooden block and two powders are added together and stirred. After a while the powders transform into a liquid and the beaker is mysteriously stuck to the block!

In this activity students find out that this is an example of an endothermic reaction. They control variables to investigate what reactants would make the best cold pack and then explain how the mystery works using ideas about chemical energy.

Learning objective

  • Plan variables: Plan a simple investigation using control variables
  • Chemical energy: Determine whether a reaction is endothermic or exothermic

    Blueprint curriculum link

    • Unit: Matter & energy
    • Concept: Exothermic & endothermic: During an exothermic reaction energy is transferred to the surroundings and in an endothermic reaction energy is transferred from the surroundings
    • Skills: Variables: Choose how to vary the independent variable and measure the dependent variable; Control variables and explain which ones cannot be controlled
    • Learning stage: Acquire

    Activity contents

    • Teachers guide
    • PowerPoint file

    The activity is delivered as a zip file. After you checkout, you will be sent an email with the link to download it.