Plans by gay education campaigners to encourage schools to make maths and other lessons more gay-inclusive have been attacked by critics.

LGBT charity Schools Out has published guidance for teachers on how they can make more references to LGBT people during lessons.

The advice is backed by the government but is not compulsory.

For example, the charity says that maths lessons can use examples of a family headed by a gay couple when discussing shopping budgets.

Another example could involve geography teachers talking about why certain cities, such as Brighton or San Francisco, might attract gay people.

The lesson plans will be available to download from the Schools Out website and are being launched as part of LGBT History Month, which takes place next month.

They are funded by a £35,000 grant from education quango the Training And Development Agency For Schools.

Tory MP Craig Whittaker, a member of the education select committee, told the Daily Mail: “We are too far down the national comparative league tables in core subjects. Teachers should concentrate on those again.

“This is not about being homophobic, because there are other schemes around the education which support the LGBT agenda.”

Daily Mail columnist Melanie Phillips wrote: “Absurd as it sounds, this is but the latest attempt to brainwash children with propaganda under the ­camouflage of ­education. It is an abuse of childhood.

“And it’s all part of the ruthless campaign by the gay rights lobby to destroy the very ­concept of normal sexual behaviour.”

The Taxpayers Alliance also criticised the plans, saying: “Parents will wonder if this is a right use of funds and time.”

But Sue Sanders, of Schools Out, said: “All we are attempting to do is remind teachers that LGBT people are part of the population and you can include them in most of your lessons when you are thinking inclusively.”