Great lesson, Linda!
When we did a lesson similar to yours, we used a crushed strip of crepe
paper (tied near the top with a bow of ribbon or yarn) for curtains, which
were glued next to the window side edges. Crepe paper provided an extra
sense of depth and looked like real cloth. Also, have the children thought
of animal life in and around the window? Cats, birds, insects are often in
the environs of a window.
Ann-on-y-mouse in Columbus
Art teacher, K-5, retired