I think every basketball coach out there does a shell drill to work on M2M defensive concepts. If not, you really should. I went through some notes earlier today and found some nice pointers on what you should be working on with your kids while doing the shell drills.
Transition Defense:
Incorporate your full court transition defense back into a 4on4 or 5on5 shell. This way, you're not only working the basic defense, but transition at the same time.
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