What about a simple 4 patch alternating with a plain block? Gives them a clue of strip piecing; no points to match up and easy as pie. Then birth and tie the quilts? Could some of the adults cut the strips ahead? I've helped my niece's 4th grade class do a similar project in the past. Have another upcoming one in a month or so. The adults did all the cutting ahead and there were no machines. All the kids sewed by hand. Since they are working with machines you should be able to get a reasonable number of quilts done, especially if they are rotating stations.