My Classroom as a Camera Obscura

The other day we made the photography classroom into a camera obscura. Blacked out the windows and door, cut a hole in the paper covering the door, inserted a uv filter, hung a white backdrop across from the "lens" opening, and turned off the lights. I really like this activity, but then again I'm a photo geek. Hopefully the students liked it too...got a few ooohs and aaahs =] The exposure time for these shots is 25 seconds. The first image is with the uv filter-sized pinhole--nice and bright, but blurry. Small depth of field? Maybe.

If you don't know what my classroom looks like the door is just off to the right. The inverted image is of the two portable classrooms across from my room. You can also see several students in white t-shirts. At the bottom right are some students sitting on the floor.

This second shot is with a much smaller pinhole--about 1 cm in diameter. Darker for sure, and I believe it's also clearer. It seems to line up perfectly with the way apertures work, but I'm not positive if that's the reason for the difference.

Have I mentioned before that I have the best job ever? Add this to the supporting evidence :)