"But how is this relating back to sound?"
One student responded with, "We saw the light do things on the ceiling yesterday, like when we beat the drum hard we saw big jumps in the light, moving bigger distances. When we beat the drum softly, we saw barely any jumps in the light. This makes me things that louder sound make taller waves and softer sounds make shorter waves."
Well said, 6th grader. Here are pictures of the actual data we collected over two 6th grade classes.