Look for: The starting position of the sound source

2.B Develop a model to describe how a force applied to an instrument causes its shape to change, leading it to repeatedly deform above and below its initial position (effect) as it vibrates and use that model to predict what a force will do to another instrument.

Inclusion of model components representing or describing, at every point in time:

• The starting position of the sound source.
• The object that applied the initial force to the sound source.
• The shape changes of the sound source.

Inclusion of interactions between components that represent or describe:

• A force that causes the shape of the sound source to deform.
• After a force is removed, the sound source deforms back in the opposite direction, extending beyond the starting/original position.
• The repeated nature of this back-and-forth-motion of the shape of the sound source.
• Eventually the sound source stops moving back and forth and goes back to its original starting position.

Use Rubric for Modeling Motion of an Object Making Sounds to assess students’ individual models of a different instrument than the class consensus model. If students are struggling to connect all the components and interactions across instruments, facilitate a conversation comparing the class model to a couple of student models and decide as a class if anything needs to be added or changed about the consensus model or the student models. This could be done the day of or after you use the rubric on each model. It could also help the class agree on a set of conventions for modeling force and vibration with respect to sound.