Many thanks to Sasha Hospitál for developing the idea for this activity.
This activity came out of a conversation with my daughter, Sasha. I explained that I had begun teaching my 8th grade class how to balance chemical equations and I sensed that my students were a bit frustrated. I told Sasha that they needed a more tactual model of the atoms (making up the molecules) involved in a chemical equation in order to understand this concept better.
The equation for which she developed this activity is used as the basis for the description, but any simple equation could be used. The size of the pom-poms should be (approximately) modified accordingly. The equation is: H2 + O2 yields H20
My daughter thought about this and envisioned using pom-pom craft balls of various sizes to represent the atoms of hydrogen and oxygen in the equation. After a quick trip to Wal-Mart for supplies, the following activity is what resulted from her efforts.
This activity should be introduced after the students have learned the Law of Conservation of Mass and the most basic information about chemical reactions and balancing equations.