Your pension is a defined benefit.
In the UK there are two main types of pensions - defined benefit and defined contribution. The Teachers' Pension Scheme is a defined benefit scheme. This means that the amount of pension you build up in the Scheme is based on your salary and how long you've paid into the Scheme. It provides a guaranteed income for life.
In comparison a defined contribution scheme provides a pension based on how much you contribute, how those contributions are invested and the success of those investments.