Create cards that have the names of a variety of musical instruments on them. Pre-record or purchase a tape that has recordings of the same instruments on it. Play the recording for the class, and have students put markers on the musical instrument on their card when they hear it played. You could also have one student go into a separate room, play an instrument and have students try to guess what it is.
Assign different motions to four different musical instruments. For example, the drum could mean move backwards, the guitar could mean move to the right, and so forth. Have one student hide a small object in a part of the room, while a second has her eyes closed. The second student will have to listen to the instruments, played by the student who hid the object, to determine where in the room the object has been placed.
Hand out a small musical instrument, such as a triangle or wooden sticks, to all students. All students should have the same instrument. Play a very simple melody with the instruments and require the students to play exactly as you did. If someone does not succeed, eliminate him from the game. Make the melodies and combinations more complex as you progress. Award a small prize to the student who stays in the game the longest.
Invite a student up to the front of the classroom and ask her to play a song of her choosing on an instrument. She can play only bits and pieces of a song or the entire song, depending on how difficult you want to make this assignment. The rest of the class must guess what song she is playing. The first student to guess correctly is the next one to come to the front of the class and repeat the challenge, but this time on a different instrument.