Not sure what this is ... do you each present a block pattern each month? Is it to be a teaching lesson? Or just a go home and make it? or whta?
If they don't practice ... they'll never get better at doing HST and QST etc. Without triangles they are missing out on so much in making quilts.
Maybe focus on the triangles ... and teach them how they can learn to enjoy making triangles ... and perfect ones at that!
Ditto on QuiltersCache for oodles of block patterns.
Good Luck!