7.2 Chemical Reactions & Energy

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For the anchoring phenomenon, students begin by thinking about how they would heat up food without having typical methods available. They see images from a real situation, after Superstorm Sandy in New York, during which people were given Meals, Ready-to-Eat (MREs) that can heat up food by just adding water. The class explores the flameless heater from the MRE in action, which seems like some kind of chemical process or possibly a chemical reaction. Students develop an initial model to consider how a flameless heater works, but they also notice some problems with prepackaged MREs. In order to solve some of the identified problems, the class decides to help people in situations in which typical heating methods aren’t available to heat up food by designing a homemade flameless heater with instructions that others could follow.

Each OpenScied unit’s anchoring phenomenon is chosen from a group of possible phenomena after analyzing student interest survey results and consulting with several external advisory panels. The MRE flameless heater was chosen to anchor this unit for the following reasons:

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• Homemade Heater Unit directly builds upon Disciplinary Core Ideas from grades 6-8 regarding chemical reactions OpenSciEd Unit 7.1: How can we make something new that was not there before? (Bath Bombs Unit), which comes just prior to this unit in the OpenSciEd Scope and Sequence. Students leverage their ideas about chemical reactions to figure out that energy transfer happens when substances undergo chemical reactions. It also builds directly upon the Disciplinary Core Ideas (DCIs) from OpenSciEd Unit 6.2: How can containers keep stuff from warming up or cooling down? (Cup Design Unit) as we use the model developed hete about energy transfer at the particle level to build a systems level model of energy transfer on which to base our homemade flameless heater designs.
• This unit includes a substantial engineering component with multiple iterations on design. Designing any device in the classroom can be costly and material intensive, but designing the instructions for a homemade flameless heater allowed for fewer specialized materials and an easier design process compared to other options.
• In thinking about who they may be helping with this homemade flameless heater, students realize that anyone in their community (including their own family and friends) are also the stakeholders and could potentially need to use an MRE at some point. Feedback from the field test indicated that students identified with the need for a device that could warm food as they reflected on times they lost power for extended periods of time due to snow storms, floods, or other large scale power losses.
• This anchor gives students to engage directly with the community about what they are learning, and an authentic opportunity to get stakeholder feedback. Students survey family, friends and other members of the community to get some initial ideas about the experience people have with MREs, any other initial ideas or questions, as well as feedback on designs and instructions.

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