The Cambridgeshire Student Connect card offers discounted rail travel to all students aged between 16 and 18 years old in full time education.
It entitles the card holder to purchase reduced rate season tickets for journeys in Cambridgeshire and beyond at a discount of 50%. There are details of the card and an application form here:
https://www.greatnorthernrail.com/tickets/discounts-and-railcards/student-connect
See here for an article about the discount at the Campaign for Better Transport.