Most music students rent or purchase an instrument when they start band. One of the exceptions is the percussion section. Too often I see students with drum sticks and little else. This really delays the learning process and some students never recover. Parents ask me to coach their child prior to entering high school so that they can get into the “good” band. And then I find that they can barely read music, and may not have any interest in learning.
Middle school students need to rent a bell / practice pad combo. Too often a student is only interested in snare drum. Students should learn how to read treble clef and work with the bells as other students are learning their instruments. The snare drum is easily learned after the student is comfortable with playing bells. Bass clef, which is used for timpani, may be introduced at a later date. The reason I suggest practice pad rather than snare drum is that there is little reason to have a solitary snare drum at home. If a student buys a drum set, they will get a snare drum at that time. Please consider your neighbors.
Have the beginning band percussionists bring their bell kits to school. Line them up in a row and have them play all the exercises with all the other students. When a concert is getting close, then assign all the percussion parts. Any one that doesn’t have a separate part will continue playing their part on bells. If it’s a concert piece, don’t be afraid to use more than one bell player. There are multiple players on all the other instruments, bells should be no exception. While it is true that once a student gets to the high school level there will only be one on a mallet part, this does not need to be true in middle school. I prefer to hear three students playing a bell part than three students playing a triangle.