Getting teens to study!

Hi all. Im asking this on behalf of my friend. Her 16 year old is very intelligent but he’s lazy and wont do his schoolwork. Any advice or tips?

Maybe not ideal but a rewards scheme of some kind? - Three hours of study equals one hour X Box or similar. An A for an exam equals bigger treat than a D - sounds like he is a smart kid but just a bit bored by school, so maybe gamifying it will keep him on his toes!