By 15 or 16 most kids will already have studied French for a couple of years so most of the materials for this age group are not for complete beginners. If you are starting from scratch, see the materials listed under Younger Secondary. Many of them are fine for older learners as well.
In Britain, the mid-secondary years are the time when students are working towards their GCSE exams, and many of the websites providing materials for this age reflect this. The BBC's Bitesize French pages provide guidance and practice activities for each part of the exam - listening, speaking, reading and writing - at two levels (Foundation and Higher). And even if you're not taking the exam, provide useful skills practice. There's also a fun game, Destination Death.
If you're taking the exam, check out the S-cool site too. It gives advice on taking the exam and practice for the topics on the syllabus - free time, house and home, food and drink and so on.
Aiglon College in Switzerland has some good exam revision activities, again organised around the topics necessary for the exam. Choose the topic which you want to revise from the drop-down menu and click on Go.
Practise your listening comprehension with some great videos from the Ashcombe School. You can also try the quizzes and other activities which they provide. And if youexchange E-mails with a French friend, check out their list of useful phrases.
The education system in Scotland is slightly different and students of this age group will be working towards their standard grade exams. The BBC Scotland Bitesize site caters for this syllabus, providing revision and practice for the exam. As ever, of course, you don't need to be studying in Scotland to find the materials useful.
The Channel Four website offers Homework High, a service where you can ask questions about French and get an answer from a teacher. They also provide some interactive activities, at four different levels, intended to accompany the TV course Extra. It's not as useful as it might be, but has a few things worth looking at. if you're in the UK, you can also see the videos on Teachers' TV.
But learning French doesn't just mean learning the language and doing exams, but also learning about the culture and customs of the country. The online resource centre for C'est a toi!provides a fun way to do so. Each activity takes the form of a webquest, during which the student is directed to a French website to find out information on French culture and lifestyle. At the lower levels the questions are in English - they change to French as the student progresses through the three levels of the course.
And if you need help planning your revision for the exams, and making sure you don't get too stressed, Revision Centre has some excellent advice.