The instructions in the McCalls Magazine would be copyrighted. This means that you cannot make 10 copies, distribute them to a group of quilters and get together to teach each other how to make the block/quilt in the same way as the magazine. You can require that these 10 people BUY a copy of the magazine and get together and teach each other how to do it by the method in McCalls magazine.
OR you can follow the instructions for quilterscache.com which i believe say that you can make the same 10 copies to use for a class and use her instructions, as long as you leave Marsha's copyright showing.