Introduce the concept of sound with students making their own musical instrument: Sound Sandwich activity. Ask them to use careful observation and familiar objects to copy the model and make their own.
Ask students, then discuss how the sound is made: the vibrating elastic band bumps against the molecules in the air, which bump each other along. This vibration of molecules travels through the air to our ear. In our ear the vibration is converted to a signal that is sent to our brain.
Model how sound travels with the Sound Vibration Model.
Do Sound with a Ruler activity, for students to explore pitch, and to introduce the concept of vibration frequency.
Play a Musical instrument to demonstrate how pitch can be changed by changing the length of a string/tube, which changes the vibration frequency along it. Discuss other instruments that students play and how the pitch changes in them.
Optional: sing a class song using an instrument (e.g. guitar, uke). Students can accompany with their noise makers.
Finish by exploring sound through solids with the Sound through solids activity.
Note that the constant noise of this class builds the energy level of the students quite dramatically.
Revamp for younger grades: ruler vibrations too subtle/complex - maybe switch out with elastic band sounds where they can see the vibration. Sound through solids maybe too obscure, also hard to manipulate.
Stuff to try: http://science-notebook.com/sound01.html