Some of you are very lucky to have so much equipment. I bet your classes love the variety! We have stability balls, dumbbells, weighted bars, benches, bands and tubes available for our group classes. If I do a circuit I can add medicine balls, agility ladder, stability disc and Bosu.
I also use paper plates:)
I love the 55-65 cm exercise ball; It is very versatile, fun, and helps to improve balance and core strength. It targets the core muscles on every exercise whether you are squatting, doing pushups, pelvic lifts, hamstring curls, or just bouncing on it. My students are always happy with the workout and their muscles are shaking when they leave.