Gerbie

If I read your post correctly, there are 20 people in your group, and each person brings 1 2 1/2 in strip, then you should only be able to make one quilt top from this. So you would have a top at each meeting, but if each of you brought a jelly roll or the 20 strips then you would have 20 tops you could do for one meeting, just a thought, depends how many quilts you want to do for charity. All could be working on JR's at the same time. In one Jelly roll I used to do my first JR quilt, there were 40 -2 1/1 inch strips, which made a decent size lap quilt. I purchased 2 jelly rolls from Hobby Lobby and each one of them only had 20 -2 1/1 " strips, with repeats of most of the strips, so I used both jelly rolls to make one quilt. Be sure to check the jelly roll you are purchasing to see just how many strips are in each one. They do differ in the number of strips.
These are quick and easy to do, just as someone earlier posted, your quilt keeps getting wider each time you bring the bottom strip back to the top to sew again, not longer. You will have to cut the loop at the bottome each time. After I sewed all of my original strips into one longggg strip, I cut my 18" or so off at the top, but I am sure you can do either end. I did not find the tute by Jenny confusing, but if it is to you, you might check out the Jelly Roll Race Video also on You Tube and watch it. I found that Jenny at Missouri Star Quilting .com was a much better tute video for my personally. If you have any problems, p.m. me and I will try and help. I have made three already, but all of the above posts seem to be very explanatory and good to me. Just have fun.