"Is that our teacher?"
Translation:Это наш учитель?
I really don't understand Это and Этот --- I thought Это was more "this" or "this is", and Этот was "that" or "that is", but Этот was marked wrong here.
Этот is used as "this (noun)," where the noun is masculine. Этот стол = this table. Это is used for "this (noun)" where the noun is neuter. Это озеро = this lake. Это is also used as a general "this" or "that" like in this example (What is this/that? This is a (noun)), and you don't you have to change the gender. Это I think has other uses as well, but you get the idea.