Supermarket giant Tesco is to teach children about food after a study found a third of under 11s think cheese grows on trees.

Britain’s biggest grocer is pumping £15 million into a “field to fork” project to take a million primary school kids around farms and factories and show them where meat, produce and dairy products come from.

The back to basics Eat Happy project comes as research by the Future Foundation revealed a fifth of five-to-11-year-olds think carrot cake or tomato ketchup count as one of their five-a-day.

Worryingly, one in five believe chicken is the main ingredient in fish fingers yet nine out of 10 think they know which food is good for them.

Launching the scheme in a blog today, Tesco managing director Chris Bush said: “There is a gap, not just in the knowledge our children carry with them but in the fundamental relationship they have with food.”

Supermarkets and the food industry have been lambasted by health campaigners for failing to help combat childhood obesity and pressure group Action on Sugar wants to see a 30% sugar reduction in fizzy drinks, treats and staples like cereals and soup.

Figures from the National Child Measurement Programme (NCMP) show that 18.9% of ten-to-11-year-olds were obese and a further 14.4% were overweight.

And of those aged four to five-years-old, 9.3% were obese and another 13% were overweight.

Mr Bush said Eat Happy is “a contribution, not a magic bullet”.

He added: “I am also realistic that some people will challenge us to have a more abrupt, immediate impact by stopping selling unhealthy alternatives which children find appealing.

“I don’t think that is a lasting solution. We will create the healthy habits of a lifetime by making the carrot more appealing not relying on the stick.”

Eat Happy will take children behind the scenes to see how veg is grown, bread is baked, cheese and butter made as well as seeing cows being milked.

Schools who are unable to take children on farm, factory or store outings will be able to enjoy a virtual field trip using Google’s Connected Classroom technology which will let them talk to UK farmers as well as growers around the world.

Mr Bush said: “This work will take a generation but if we get it right, and I believe we are, we will be helping to break habits formed over several generations and create a healthier future.”

The scheme was welcomed by charity The Children’s Food Trust which campaigns for healthy food for all kids.

Chief executive Linda Cregan said: “Parents, schools and food retailers and manufacturers all have a responsibility to make sure our children are eating healthy, nutritious food.

“If our children grow up with an understanding and interest in both cooking and eating healthy food, they have the best opportunity to reach their full potential.

“Being overweight or obese from an early age puts our children at a massive disadvantage from the word go.”