Lesson Plan

Some Like it Hot!

#STEMChallenge Knowing about phase changes and thermal energy transfer inspires designing a reusable handwarmer.
Donna M.
Classroom teacher
Vista Visions Academy
Vista, United States
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My Grades 6, 7, 8, 9, 10, 11, 12
My Subjects Science, Health & Wellness

Students will be able to...

  • Describe what the phases of matter (solid, liquid, and gas) look like at the atomic level.
  • Explain how the forces of attraction are what keep atoms in a particular phase at a specific temperature.
  • Explain how the input of energy into a system affects the state of matter.
  • Design a hand warmer that meets design requirements and constraints.
  • Share the design publicly and evaluate competing designs.
All Notes
Teacher Notes
Student Notes

1 Hook

Hook students with an example everyone can relate to - themselves! Use the video found on the National Geographic Education website, "U.S. Cold Snap: What Do Bitter Temperatures Do to the Human Body?"  to encourage students to think about why and how people stay warm in cold weather. 

  • Discuss different ways in which humans maintain body temperature. Conclude the discussion by introducing the problem - We are taking a trip to a cold climate. Create a low-cost handwarmer that is small and efficient. Discuss  and come to consensus on the criteria and constraints.  For example,
  • It should be no larger than 10 X 15 centimeters. 
  • It should reach a temperature of at least 40 degrees Celsius.
  • It should maintain that temperature for at least 5 minutes.
  • It should cost no more than $2.00. (If you wish to develop a price list for materials)

2 Investigate

Investigate the phases/state of matter by examining the relationship of heat and temperature and the resulting molecular motion Background information  can be provided in a number of ways depending on the grade level and prior knowledge of students.

Simulations: Molecular Workbench: "Heat and Temperature," activities 1-5 (linked above) are simulations in which students explore heat and temperature, kinetic energy and changing temperature. Only works on computers/laptops.

Simulation:  Phet "States of Matter Basics" is a simulation that  provides background information on molecular motion in each state of matter. It is written in HTML 5 so can be used on iPads and/or Chromebooks as well as laptops. Downloadable teacher directions and student sheets are available on the site.

Alternatively, the ExploreLearning Gizmo, "Phase Changes,"   can be used to explore the same concepts. The Teacher Guide and Student Pages are available on the website.

Once students have learned about or reviewed the states of matter and phase changes and how they are affected by temperature, introduce the Bozeman Science video, "Endothermic and Exothermic Reactions." Depending on the grade level of students, you may wish to explain the energy that is released when bonds are formed in a chemical reaction is greater than the energy that was released when the bonds in the original reactants were broken.   

3 Plan

Students develop a plan to create their own handwarmer. First they are provided with science background about how handwarmers work from  the  HowStuffWorks site. 

Then, in groups, students brainstorm how to create their own handwarmer. They record their ideas on a shared Google doc. Depending on the grade level you are working with, you may wish to inform students what materials they will have to work with or let them explore a wide range of possibilities that they find in their research.

Students should develop a plan for creating and testing a handwarmer. The goal is to use the optimal amount of materials to develop an efficient handwarmer within the design constraints. Allow students to develop the constraints and criteria and could include cost, size, efficiency, etc. Students can document their work using a design cycle such as:

  • Define the problem
  • Investigate
  • Plan
  • Create
  • Evaluate

You may make this as open or directed as appropriate. Students can plan their initial tests and determine the amounts of each chemical they will use and the size of their handwarmer. They should include what tests they will perform and the qualitative and/or quantitative data they will record.

4 Create

To have students create the handwarmers - Gather the necessary materials for the class.

The directions linked above are for a reusable handwarmer. This is for teacher use. Depending on the grade level and design experience of your students, you may wish to let them explore the amount and ratio of chemicals they will use. They should follow their written plan, test each iteration, and record their data in their shared Google doc.

5 Evaluate

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Students evaluate their handwarmers . Once they have explored the optimal amount and combination of chemicals, they test each iteration, and record the qualitative/quantitative data  in their shared Google doc. Additionally, they will design a vinyl pouch for the chemicals. You may wish to have them decorate the pouch using colored permanent markers or sewing or gluing a cloth envelope for the vinyl pouch. The decoration can be assessed using art design criteria and standards, making it a STEAM activity rather than a STEM activity.

6 Present

Presenting their design to the public is essential for feedback and comparison of designs. Students have a choice of tech tools they may use to present the handwarmer. In their presentation, students detail the design process and share the data they collected.

As a class, students develop  a  process to determine how well the handwarmers meet the design criteria and constraints. They compare the designs and evaluate each one.

Higher level students can prioritize the criteria and decide upon tradeoffs. For example, they may decide a larger warmer is OK if it stays warmer longer. Older/more advanced students can evaluate the handwarmers for cost, safety, reliability, and aesthetics, as well as possible environmental impacts.