Schools minister Nick Gibb said: "The cost of the teachers' penson alone is forecast to rise...The teacher's pension is still one of the best available and nobody within 10 years of retirement will be affected by these reforms.
"But there do have to be reforms as people are living longer and as a consequence a defined benefit pension is very costly."
Thousands of teachers and lecturers have launched a 24-hour strike in the continuing bitter dispute over the Government's controversial public sector pension reforms, closing schools and disrupting lectures.
The action by members of the National Union of Teachers (NUT) and University and College Union (UCU) in London has hit over 60 higher and further education institutions and a number of schools.
Parents have been forced to make alternative childcare arrangements or work from home.
Health workers and other public sector staff across the country are staging protests and demonstrations amid continued opposition to the planned pension changes.