These are articles I've found that I thought might contain helpful advice. A lot of the 'activities' listed in them are aimed at parents of younger children but much of the advice is applicable to children of any age. Your teenagers will also need routine or no routine, play, social contact, fun activities and fresh air.
How to start thinking about what you're going to do at home with your kids. Simple and short. Some good ideas about easy activities to do with small children.