OH MY!!!!! This is way too funny. My poor mother! It wasn't "D"s, just "unsatisfactory".
I went to parochial school 1-8th grade, and we all knew that we couldn't get away with much... the nuns simply didn't tolerate any nonsense. THEN, I went to public high school. I quickly learned how to confound and torment the teachers. The goal was to spend as little time as possible in the classroom, without getting into trouble like the dummies who would cut class. I deduced that the straight "A"s were a license to be as irritating and distracting as possible. They couldn't accuse me of not doing my work; I would intentionally have it done ahead of time. Ergo, it was easier for the teacher to send me off "to the library" or just dismiss me from class, in order to get me outta their hair.
Once I was sent to the school counselor (back then we only had one, but she sure knew everybody) by a not particularly wise teacher. When I cheerfully arrived at the office, the counselor asked, "What are YOU doing here?". I responded that I would like to know also, since I had completed all of my work and could hardly be accused of slacking off. As a matter of fact, I had brought some magazines/games/deck of cards (I don't remember what it was that particular day) to class in order to keep occupied. LOL. The counselor tried to hide her amusement, but didn't do a very good job. She just let me hang out for a while and then sent me on my way. I was never sent back there.
That teacher didn't want to give me the satisfaction of getting out of class, so she spent the semester trying to maintain order (everybody else thought this was very funny, therefore class attention was not on the lesson plan).
What happy memories! Today's kids are really missing out. :-)
Haha... My husband always tells a similar story - a substitute teacher sent him to the high school counselor one day when she caught him doing something (I forget what) in class. The counselor sat him down and called for his file, all set to read him the riot act. When he opened it (I guess expecting to see suspensions but seeing a perfect record and A's, instead), he just looked at him a second, then just closed the file and said: You can go back to class, son.
BTW, I was one of those dummies who cut class all the time. I spent more time in in-school suspension than my classes in 11th grade.