Whenever my middle school gym teacher didn't have anything planned for that day's class, he'd tell the class, "We're going to play dodgeball today." Looking back, it seems as though we played dodgeball half the time.
Treble and bass clef flashcards were my seventh and eighth grade chorus teacher's equivalent of dodgeball. It always seemed that when the teacher was running low on inspiration, he'd say, "We're going to do flashcards today." Three stools would be set up. The teacher sat on a stool across from the student, while placing flashcards on a stool between them. The student was supposed to name the note on each card as quickly as possible. Thus, those who didn't know the names of the treble and bass clef lines and spaces got to know them extremely well by the end of the semester. I was puzzled when he asked us to spend one class hour "talking about the lines and spaces." (I don't recall any exchanges between students such as, "Say, did you know that B is the third line of the treble clef?" "Why, no, I'd forgotten that. Thank you for reminding me.") Students spent that hour just talking or doing homework. For a chorus class, we did very little singing, but everyone should have known the treble and bass clef notes by the end of the semester.