A few years ago I saw a teacher in my district present a lesson on using hula hoops to reinforce BAG on Soprano Recorder. (I feel awful, I can't remember who gave the presentation, I'd love to give her credit.)
Basically, you need 3 hula hoops laid out in a column on the floor. Each one represents one of the pitches; B, A and G. The hoop that is farthest from the students is B. My hoops are different sizes because I found them at the dollar store. I don't really care about the size difference but I do like to use different colors when I do this. I find that the dollar store hoops are good for this because they are smaller and easier to jump if you want to do a skip from B-G.
I start the warm-up as the conductor. If I am standing in a hoop, students respond by playing the appropriate pitch. If I am not standing in any of the hoops, then it's a rest. After my turn, I select at least 2 students to take turns as conductors.
This is an easy little warm-up and a good way to review fingerings for BAG.