Great activity to help students visualize sound as a mechanical energy, vibrations! This activity is quite easy to do, and the materials are easy to get from around the kitchen. The video in the directions demonstrates the activity with a balloon which is also a great option. Students can further explore sound waves by observing how the grains react to high pitch or low pitch sounds, then discuss the differences in movement. Another way for students to observe sound is by feeling the speaker of a sound system or car speaker, the sounds pulsating on their hand from vibrations. Overall, this is a great activity to help students understand how sound works.