Great visuals and details on sound waves. The lesson was also presented in a way that was easy to understand and built upon each other. The two activities are great enhancements to understand sound waves and pitch; first observing the sound vibrations hand out gives students an opportunity to compare a high pitch and low pitch sound, then modeling a vibration with a string actively engages students in making a wave with their hand and arms. Also, the extension activities with the online oscilloscope gives students a first-hand experience with making sounds into their computer microphone and seeing it as a wavelength. Overall, this is a fun and engaging activity for students to explore on their own.