i'm gr1-3 so you will have to judge what's right for your level, and what might appear too childish, but I just got a bunch of these alto resonator bells which are one octave lower than soprano resonator bells. They are way cheaper and more portable than standard Orff instruments so you can get enough for the whole class. I use them for learning basic melodic figures, chord theory, and as part of an ensemble with full-size Orff instruments. I actually prefer working within one octave and have removed the bars beyond one octave from my Orff instruments- to be added on only in certain circumstances.