They're/Their/There

I can only blame the teachers. And the parents; let's not forget the parents, who all to often don't know the difference themselves. The American educational system is profoundly broken, yet the Teachers Unions want to be paid better and furthermore, never be taken to task ever, even as they're graduating students who don't know the difference between these three sentences:

1. They've forgotten their bags.
2. They've forgotten there bags.
3. They've forgotten they're bags. 

In response to the next atrocity of language in re the topic, I'll send the offender the following quiz and require a 100% passing grade before I reply.

I am prepared to make many (more) enemies.