Meaning of this sentence? Use of 所

I don't understand what this is supposed to mean
わからない所考えるようには言われたけど写させていいとは言われてない
Also what is 所 used for here?

Full part: わからない所考えるようには言われたけど写させていいとは言われてない

I think she doesn't want to let students copy her report?

Here is another sentence with tokoro:
あいつも私の知らない所で勝手に背長していっちゃう...

What's the context? That sentence can have two different meanings.

Can you get the meaning of され, BTW?
What does the され mean in this sentence?