Students' conceptual understanding of chemical reactions is foundational to much science learning. Understanding atomic level reactions is crucial for learning physical, life, earth, and space science. Even more importantly, they open up new windows of curiosity for students to see the world around them. By seventh grade, students are ready to take on the abstract nature of the interactions of atoms and molecules far too small to see.
To pique students’ curiosity and anchor the learning for the unit in the visible and concrete, students start with an experience of observing and analyzing a bath bomb as it fizzes and eventually disappears in the water. Their observations and questions about what is going on drive learning that digs into a series of related phenomena as students iterate and improve their models depicting what happens during chemical reactions. By the end of the unit, students have a firm grasp on how to model simple molecules, know what to look for to determine if chemical reactions have occurred, and apply their knowledge to chemical reactions to show how mass is conserved when atoms are rearranged.
Embedded in this unit are a variety of assessments, including self, peer, formative, and summative assessment tasks. This unit concludes with a transfer task in which students apply what they have figured out to two different related phenomena, elephant’s toothpaste and the crumbling of the marble that makes up the Taj Mahal.