Answer: Not much.
Instead of using their time to learn valuable skills and having fun they are sat doing stressful revision for a school they are under a lot of pressure to do well for.
In my opinion, there are 3 things which should be added to the secondary school curriculum. The first one is not something which students can be graded on at the end of the year. It is interview techniques. When teens leave secondary school they have had no/little experience getting interviewed for things like jobs, colleges and universities, so one hour a week being taught about what an interviewer is looking for would do student a world of good in my opinion.
The second thing which should be added is something which pupils would be tested on. It is Computer Science (stuff like programming). The end of year tests wouldn't have to be hard however as long as the future generation are learning the basics of how to write HTML and how apps worked would be a huge advantage for the app and website industry as it is one of the biggest growing industries at the moment.
The 3rd thing which should be added is joke writing and telling. It has been scientifically proved that the more you laugh the longer you will live. It also makes people happy and puts them in a positive spirit. This class wouldn't need to last long and it wouldn't need to have much structure but I can speak for all teens around the world when saying that pupils love to enjoy school. It takes the pain of revision and the pressure of exams.
So if you are reading this Mr Gove, please feel free to use some of my ideas.