There was a time when it was considered important to teach children to sort instruments into categories such as aerophones, membranophones, idiophones and the like. It can be done in a classroom with lots of kids who, because they never get to touch (or even see more than a picture of) any of the instruments, will not disturb those trying to do maths in the classroom next door. A good five minutes could be spent debating whether a piano was a chordophone (because of its strings) or an idiophone (because the strings are hit with hammers).
Most children, and especially boys, love to hit things. Using a beater rather than a hand allows greater force to be directed to a precise point. This can produce both greater volume and resonance. Most things can be hit with just a stick but this can cause damage, especially to membranophones where the skin (or plastic equivalent) can be punctured.
So before we get into making drums, cymbals and other percussion from material destined for landfill or recycling, let's make some suitable beaters. A plain stick does for many things, especially metal objects. Find your stick, broom handle or whatever and cut it to the appropriate length. Try one foot (30cm) to start with. The thickness of your stick will have a bearing on its suitability. A length of broom handle may be fine for a steel hub-cap (if you are lucky enough to find one in the plastic age) but will be too 'heavy' for a biscuit tin. I'm not saying you can't use a heavy beater for a delicate object but doing so will restrict subtlety.
Wrapping the end of the beater in rubber, cloth or string will soften it. Whereas this is usually undesirable when hitting another wooden object, for many applications it allows the resonance of the instrument to be heard, making a more rounded sound in which the moment of impact is less pronounced. By wrapping one end of the beater in rubber you retain the option of using the hard end if that produces a more pleasing sound.
Javanese and Balinese gamelan makers whip their beaters with cord. I have seen many beaters from African countries that have had pieces of car tyre or bicycle inner tube attached to their ends. It is obviously a question of using what you have to hand. In England the Post Office uses copious amounts of rubber bands to hold letters in bunches to make delivery easier. To avoid breakages and the inconvenience that would entail, they only use each band once. Far be it from me to accuse anyone of littering but many of these end up on the pavement. (Or you can just buy some from a stationers - perhaps a more hygienic option.)
Put your beater through the loop in the band and, starting about a centimetre from the end of the stick, pull the band tight against the wood. Twist the band and loop it over again. Repeat this, twisting and re-looping each time. Add another rubber band and repeat. It's really much more straightforward than it sounds.
The finished beater in the picture was made with a 25cm (10") length of 12mm (half-inch) dowel used six rubber bands. The heads don't fly off like those from the catalogues, maintenance is a no-brainer and, if you involve your students in the making, they will be treated with respect and wielded with pride.