All of the revised models (Artifacts A, B, C, D) represent sound waves with crescent lines and include air particles in their models. It is noteworthy in Artifacts A and B that this symbolic representation of a sound wave differs significantly from their initial models, suggesting that the radiating crescent is an intentional change in their conceptual thinking about how sound travels. Artifact B also shows a change in how the student understands the multi-directionality of sound waves coming from a source. Artifact C (with the revised, second model on the left-hand side) shows dots for air particles clustering around the radiating crescent lines, suggesting the physical account that the crescent symbol means an area of compression of particles.

Student thinking also suggests a variety of potential causal explanations for the glass breaking. Artifacts B and C offer the clearest evidence of the causal story between the vibrations caused by the boy (specifically, his vocal chords) creates sound which travels then through air particles until they collide with the glass surface and cause the glass to vibrate. Artifact A indicates that it is due to the molecules “moving faster to cause it to break,” but does not specify how this movement is related to the volume (amplitude) or pitch (frequency) of the sound. Artifact B suggests that pitch matters, whereas Artifact D makes a connection to the amount of energy (despite less clarity about which wave properties might affect the amount of energy).