Here's our version of the activity advent calendar:
After printing the two calendar pages, fill in the activities.
Perforate the "doors". I used my sewing machine without thread, at a stitch length of 1.6. The back looks like a bunch of "I"s.
Line up the two sheets, holding it up to light to match the squares, and attach. I stitched the top and bottom.
I stitched bias tape, about a 36" piece, onto the sides leaving a hanging loop at the top.
And I could not stop myself from opening the first little door. Which is so cheating. And reminds me of opening the doors on my chocolate advent calendar as a kid and hoping my Mom didn't notice.