You're running a choir rehearsal. It's a long work with multiple movements and you've been working on it with your group of singers for a very long time. You get to a movement you haven't touched for awhile when the complaints start to bubble out: "We haven't learned this yet! You haven't taught this to us!" The tension soon reaches a boiling point as indignant students create a coalition against you and in defense of their own bad memory. The only problem is, you have taught this to them. Probably twice, and you know it. Some of the kids are even backing you up. But the seed of doubt has already been planted and the kids who claim ignorance have probably even wiped their memories clean in order to destroy incriminating evidence. Now you as the teacher get to waste time re-teaching the same old thing.
Nothing sends me into a Bruce Banner Hulk-rage faster than hearing the "You didn't teach me that" refrain. I mean, sometimes it's true and I haven't taught a particular section or concept to my student. This is bound to happen when I've got around 35 students at varying skill levels. But the legitimate "don't know what this is" claims are far outweighed by the mass-amnesia "You are a cruel and powerful teacher" claims.
I haven't found any solution to this problem. I have a theory that it has roots in the desire for younger people (especially males) to show their dominance over every other living thing within sight by either physically intimidating them, hurting them, or conquering them with volume but I could be wrong. The hardest part is not becoming defensive and shouting back at the kids "I DID TEACH IT! I DID!"
There are four things you can do:
2) Teach your students absolutely everything all at once.
3) Be the best planner in the entire world and never deviate from that plan.
4) Eat ice cream, the balm for hurt feelings.
Remember kids, Teachers Have Feelings Too.