making grammar interesting for teenagers is quite a difficult task. As to practising grammar what I find useful is The grammar activity book - Bob Olbee. There are many funny and interesting activities and games suitable for high school Ss. When I present some new grammar I use very often MIND MAPS. I think it's perfect for keeping Ss awake and it also help them to concentrate more and remember the new grammar better and faster, you can use a lot of colours and pictures and in my experience Ss love it!