The '50s were a different time. When I was in third grade, I think it was 1959, I got to go to Mrs. Spencer's Workshop for part of each day. This was a special

The '50s were a different time. When I was in third grade, I think it was 1959, I got to go to Mrs. Spencer's Workshop for part of each day. This was a special class where we could make up our own projects and do them. I wanted to make a printed circuit board for a science fair project, and I wanted to etch it myself. I didn't have a source for a phenolic board with a copper layer, but I figured I could at least demonstrate the concept by masking both sides of a copper sheet with electrical tape as a resist. So I asked Mrs. Spencer if she could get me a sheet of copper, some electrical tape, and a tank of nitric acid. And she did! I masked the copper with the tape and dunked it in the nitric acid, and watched it dissolve the copper. Then rinsed off the copper, peeled off the tape, and glued the copper strips to a cutting board to make the circuit. (I figured the cutting board would satisfy the "board" part of "printed circuit board".) This was the best third grade project ever!