Glockenspiel notes

To obtain the glockenspiel keys (which are expensive), music teachers replace their collection as the pads wear out.
Old glockenspiel keys that have lost their pads can be repaired: obtain sticky felt pads made to go under the base of chair legs, and cut them to size to replace the glockenspiel pads. To make a cheap mallet, tightly wrap a thick elastic band around the wide end of a chopstick.

Hand out glockenspiel keys and mallets to the students.
Ask students to compare their note to their neighbour - help them hear the higher and lower notes (which can be tricky for a novice ear).
Students may need to be spaced out to hear their own sounds over the rest of the class.
Then ask students if the longer glockenspiel note is lower or higher than the shorter glockenspiel note. Once all students have arrived at a conclusion summarize what they find: the Longer note makes the Lower sound (both start with L).

Relate the glockenspiel length and note change to other instruments:
On a ukelele or guitar or violin, a longer string makes a lower note than when the string is made shorter by placing the finger on it.
Note that the size and tension of the string also makes a difference to the note made, so this comparison should only be made using a single string.
For wind instruments, the longer larger instruments make lower notes than the shorter smaller instruments.
On a piano, the lower notes are made by longer strings.

Discuss how the glockenspiel notes make a sound:
When the bar is hit by the mallet it starts the bar vibrating.
The vibrating bar makes the air molecules around it vibrate. The vibrations travel outwards from the bar until they reach our ears. The vibrating air molecules makes our ear drums vibrate, so that we can then perceive the sound.

Students can visualize the vibrations of the glockenspiel bar by placing small rocks on the bar. (Note: this will chip any paint on the bar.) When they hit the bar with the mallet the rocks bounce up and down. The rocks continue to bounce as the note (and vibrations) linger after the first hit.