Exploration of making and changing sounds is part of the first-grade performance expectation 1-PS4-1, "Plan and conduct investigations to provide evidence that vibrating materials can make sound and that sound can make materials vibrate" (NGSS Lead States 2013, p. 10; see Internet Resource). Early learning experiences build toward understanding in later years. Feeling objects vibrate as they make sounds helps children understand that sound moves through materials, even though they cannot see the sound waves. These experiences help young children begin to understand that sound is generated by motion. For this activity using a homemade rubber band instrument, teachers should be prepared to help children document all of their actions. With guidance, children can describe what happens to rubber bands when stretched, list the ways to make sounds with the rubber band instrument, and notice how sounds change.