One question I've found that often works with children is "What would you do if....."
In this example, the question would be, "What would you do if you stayed home all day?" Get him to imagine all the things he would do. This will help ease him into a discussion of things he will do at school as well as a discussion of how those things will still be there at home when he has completed school.
I remember seeing a teacher do this to a child I was trying to calm and it was a lesson that really opened my eyes. She was 6 at the time. A minute or so after coming to school, she started screaming and wanting to leave to go with her mother. (Who wasn't there anyway at the time). I held her, to comfort her as much as not let her just run out the door. She was hysterical, not talking to me, and I thought it would just take time and patience to let her get it all out because no trick I was doing was working.
The other teacher came over and said, "It sounds like you really miss your mom. What would you do if you could be with her right now?"
The girl started saying stuff she would imagine she could do (as if working moms have time to drop their kids off at school then go to the park, eat ice cream, and swing on the swings for a few hours while they wait to pick up their child.)

The girl calmed down as she started talking about it. The teacher simply said, "That sounds like fun. Maybe you can write a book about it later when we have our work period and you can read it to your mom tonight."
Talk about an instant change in the child....