For skill! There are four parts to DofE (I'm going to explain it all and just assume you don't know), skill, physical, volunteering and the expedition. You do an allotted time on each part (you can do them all at once) and it's pretty open what you do with them but as you go through the awards (Bronze-Gold) what you get out of them has to be slightly more challenging.
This probably explains it better than I ever could -
http://www.dofe.org/go/timescales/ (scroll to the bottom with the tables).
For Bronze: I did cooking as my skill for three months - I made varying cakes and biscuits and added things to them to make them better, tried different icing techniques and then did a quick survey to people who ate them to rate them and decide which one was my best baking fete!
I did badminton as my physical for three months for an hour a week.
I volunteered at the local Girl Guiding Rainbows groups for an hour a week for six months.
Finally, for my expedition I did a two-day expedition on Dartmoor (it was quite fun except from the fact we did our mock during flash flood warnings last year in July and our actual in the scorching heat in September).
I'm going to skip silver because it's too late to join this years entrants where I do it and if I do silver next year, I'll be doing gold until the very end of year 13 so I'm starting gold in September and I'm doing the same volunteering, learning French for my skills and I'm not sure on my physical yet! Sorry for the long post!