One important property of energy is that is can change from one form to another. The amount of energy in a closed system always stays the same. A misconception may include that students do not think of heat as energy.
Students will explore how chemical reactions can be either exothermic (releasing heat) or endothermic (absorbing heat) (MS-PS4-2Develop and use a model to describe that waves are reflected, absorbed, or transmitted through various materials.)
Students will be developing models of heat transformation by carrying our investigations. (SP2 Developing and Using Models) (SP3 Planning and Carrying Out Investigations) They will experience heat transfer. (SP7 Engaging in Argument from Evidence)
Creating Heat Materials List
We begin this lesson by activating prior knowledge. Research supports using prior knowledge as a hook for new learning. Students can connect and remember new learning longer if it has a connection to prior knowledge.
We begin this lesson with the Turn/Talk/Record strategy we used in Checking Temperatures. The students will turn to talk - engage in scientific discourse - with their elbow partner.
Students answer two questions to start the lesson
As a class we regroup and discuss energy transfers. Students have a lot of experience with gravitational potential energy and kinetic energy. Since many students love roller coasters this is no surprise. What are other types of energy transfer - chemical energy -> electrical energy -> sound energy, chemical energy -> electrical energy -> light and heat energy, kinetic energy -> electrical energy.
The rest of the lesson is self-explanatory and students manage themselves as they complete the tasks energy changes to heat energy.
Students work in partners to complete the lesson. They are exploring the conversion of mechanical energy to heat energy when they rub their hands together or stretch the rubber band. Students may have done these activities on their own many times in the past but have not considered the energy transfer that is taking place.
Students also explore how chemical energy can turn into heat. By adding yeast to hydrogen peroxide, the yeast will break down the hydrogen peroxide. Heat will be released when the chemical bonds break.
In this video, I explain why a simple lesson such as this one is an important step in conceptual understanding.
I ask and answer these questions out loud. I am modeling for students thinking beyond this lesson. I am also assessing what my students know and understand about chemical reactions. There are not volunteers to answer the questions below and did not have any volunteers attempt to answer the questions. Exothermic and endothermic are new ideas for my students. We will delve deeper into heat related chemical reactions when we experience the lesson: Changing Temperatures -> Chemical Reactions.
An exothermic reaction is one that gives off heat. What are some examples of exothermic reactions? Freezing water, formation of snow in the clouds.
An endothermic reaction is one that absorbs heat. What are some examples of endothermic reactions? Melting ice, photosynthesis.