Alex Anderson has a book, "Start Quilting," that would be perfect for your class. She shows six different quilt blocks, and then she makes them into a quilt that is 40 1/2" x 40 1/2". They are: Friendship Star, Log Cabin, Nine Patch, Rail Fence, Flying Geese, and Nine Patch Variation. The NPV has a four patch in each corner, a darker square in the middle and light squares separating the four patches. (Sort of an Irish Chain.)
There are 6" blocks in her book, or you could make them any size. For beginners, I would think it would be better to have a larger block.
None of these are difficult. When the class was over, they could actually make six more quilts out of these patterns.
She shows a quilt made from the Nine Patch plus the Nine Patch Variation.