Brian asks students to draw how they predict the particles of propane gas will be arranged inside of a tube connected to a speaker if a sound is played into the tube. He has students come to the chalkboard to draw their ideas. He then demonstrates a few different sounds with the Rubens’ Tube apparatus to help students visualize how the particles of gas are arranged differently when different sounds are made. This demonstration proves to be critical for students’ sense-making about how a compression travels through a gas transferring energy.
Brian teaches students to utilize the GarageBand program on their laptops to collect information about how the sounds from tuning forks vary when the sound travels across different distances for different periods of time. Students record information about the volume (or strength) of the sounds and the pitch (or key) of the sound from two different tuning forks. Students then draw diagrams of sounds with different pitches and volumes using two representations: 1) sound seen as a pulse moving through a Slinky toy, and 2) sound seen as a compression moving through air particles. You can see a sample of student work on the Investigating Pitch and Volume assignment. Brian circulates throughout the GarageBand lessons using backpocket questions to help connect the activity to students’ emerging ideas about sound and to push students to continue to refine their models of how sound works.
Discussion Questions: 1) The Rubens’ Tube demonstration ultimately proves to be very important for student thinking about sound waves. Why is this demonstration important for helping students make sense of sound? What is it exactly that this demonstration helps illustrate & what evidence does the Rubens’ Tube provide? 2) Take a look at some of the students’ drawings at the end of the Investigating Pitch and Volume activity. In what ways are students’ ideas about sound beginning to shift compared with their original drawings of musical instruments and tuning forks? In what ways are some students still struggling to understand sound?