At the moment, Oyster photocards for 11-15 year olds are free for London residents, or £5 for people who live outside of London, where the £5 goes onto the card. It has been like this for a while.
This is a deal, as they are going to cost £10 from September 1st, and that £10 is an application fee - it won't be credited to the balance on the card.
They give free/cheap travel in and around London, specifically:
* Free travel at any time on buses and trams
* Child fares on the Tube, DLR, London Overground and National Rail
You can apply if you are:
* Over 10 years and 11 months
* And under 16 on 31 August before the start of the academic year
If you live in London, you need to fill out a form and take it to a Post Office and get the card in 2 weeks. If you live outside London, you can fill it in online and get it in 3 weeks.