There are shapes everywhere! Sometimes they are hard to spot. I took the shape of the week flashcard and we walked from room to room looking for that shape. If he pointed to something that wasn't the shape we were looking for, then I told him the correct one and reminded him what shape we were looking for.
The point was to focus on the shape of the week, not all shapes-though that could be a fun review activity.
He really enjoyed it and I plan to do it more often.