Just a diff perspective - similar to Quantum's I guess.
When I was in high school this happened to me too but in English.
I was not 11 and at the preparing for university level so I'm aware it may not be 100% relevant...
When I asked about it, the teacher told me that it was an important life skill to be able to determine what was being asked and provide the relevant answer. Being concise is important and something that I had to learn, providing interesting and correct, but ultimately irrelevant facts was something that continued to hold me back in higher education and I know caused much annoyance with my coworkers. It drives my husband batty!
I'm not saying you are wrong to be frustrated, or that the teacher does know the material - however this can be a teachable moment for your ds - particularly if like me your DS is prone to show their knowledge....
