How about trying some 9-patch blocks (make sure the squares are all cut the same size and with 90 degree corners!)
and have her aim for straight, consistent seams?
It won't really matter how wide the seams are if they are consistent - and with practice, she may be able to sew a narrow seam consistently.
If she is after a quilt top that lays flat and won't fall apart, some consistency does help.
Maybe you could have her pretend that she is driving a car and she doesn't want to veer off the shoulder and into the ditch.
Or just have her practice 'steering' with an unthreaded needle on paper.