I am using bands to do some basic exercises to keep my basic strength level up. You can purchase on Amazon. There are a variety of colors that have different levels of resistance.
At school we used green bands, thinner than the red one I am using. Once you have them, there are videos on You Tube that demonstrate some of the various strength skills to incorporate into your routine. All students and parents can use. Remember that for students who are still growing, we want natural resistance for endurance, NOT hard to do strength.
10 to 20 reps, 3x is a good amount. If you can only do it 3 to 5 x then it is too much and you need to do less.
Good luck, stay strong, be active