Did you allow for seam allowances ("the shape pattern was provided to use for cutting") on the fabric you cut from the shapes?
Personally, as a long-time teacher, I do not consider anything with bias angles/set in seams to be "easy for beginners" and without specific instructions I do not include them in my beginning quilt design classes. It's easy to get discouraged at first and I try every way possible to eliminate that possibility for my students while still making the design/construction process fun and enlightening!
Jan in VA