My 10 year old has become forgetful.?

He is becoming more intrested in what he wears to school and friends than his homework or paying attention in cl. How do I explain that school and getting his work done is the more important than how he looks being more intrested in friends without damaging his social spirits? What can I do to help him find a healhty balance between school and social skills? With out degrading what I know is a very important part of a ten yearold boy's life.