To help students understand how timpani can be tuned, demonstrate the effect of membrane tension on pitch. With a coffee can drum (see lessons on Untuned Percussion), pull on the edges of the drumhead to put varying degrees of tension on it, while a student plays a steady drumbeat on it. Students can get into pairs and take turns exploring the effect of tension of skin on the drum’s pitch.
Have a look at the keyboard percussion instruments, the xylophone, marimba and Glockenspiel, and show the students how they are laid out just like a piano. Have students make a “paperphone.” Students can cut out rectangular bars of continually smaller sizes out of paper and glue them to thick cardboard or a large sheet of paper. You can then put labels on the bars. These make great music lesson planning tools for percussion instruments.
Show the students how resonance amplifies the sound of a musical instrument. Take an individual bar from a xylophone or Orff instrument or something similar and strike it both by itself and over a a hollow tube (e.g., PVC pipe). It may necessary to have a go first with the instruments around the school first to make sure you can clearly demonstrate this using your instruments.
Recommended listening: Camille Saint-Saëns, Danse Macabre. The composer gives the xylophone a prominent part at 1:45 and 3:45 (may vary slightly depending on the tempo of your recording). It is meant to convey the rattling bones of a dancing skeleton.