Here is an entire unit on sound complete with lesson plans and 4 activitie for students to explore concepts about sound such as: frequency, pitch, sound waves. Common Core Standards also included. Objectives: The students determine what makes a sound loud or soft, conclude that sound travels in waves, demonstrate the effect that length has on the sound of a vibrating material, demonstrate how frequency affects the pitch of sound, and create an instrument that produces sound.
Sound Sandwiches are really simple "instruments" you can make with craft sticks, straws, and rubber bands. Use them to help students recognize how to make sounds through vibrations and how they can change the pitch of sounds. Website has videos / demos to help construct and use as a teaching tool.
A Pan Flute. Shorter pipes produce higher frequency sound waves and a higher pitch. Good activity when you teach a unit on sound. The link gives you exact measurements to make notes in a true scale so you can play songs. The shortest straw must be exactly half the length of the longest straw.