When I was a math student, I loved when my textbooks had answers in the back. If I got a question wrong, I challenged myself to figure out what I did wrong, and more often that experience made for stronger learning than if I got the question right. It was a major bummer when my textbook only had every other answer, and I couldn’t figure out an answer. I like my students to be as self-contained, self-motivated, responsible for their own learning as they can be. I set up math stations that students can move to throughout our math time, (see this post). I usually have task cards at one of the stations that they can work on with a partner. I like to provide answer keys that they can learn with. Answer keys with just an answer are just fine, but by adding in explanations it’s a chance to to sneak a little extra learning, without me having to be there.