BTW, I looked like a TOTAL weirdo taking a picture of this. Just so you know.
The second circuit I did was a 4 input, 4 output (BCD to excess-3 converter) using only NAND gates. I got the whole thing done (slightly more complex than the one in this picture) and when I tested it, 4 out of 9 outputs were wrong. Uhuh. And so the guy is like -- now you debug it.
Look at that. You debug that mess of wires -- I'd rather just start over. After a lot of checking the voltage to certain gates, we noticed that I was using the wrong chip. Yeah. And the he acted like I was an idiot. Hey, someone put that chip in the wrong drawer -- not my fault.