How heavy? And what do you do with them?
I’m using 6kg dumbbells; we did squats and shoulder presses, upright single arm rows, upright rows, single arm chest presses, bicep curls and triceps extensions, along with some cardio activities, such as jogging a square, with star jumps, skaters, etc at the corners....
It’s not that hard, and each person works with weights that suit them.