Almost a third of British primary students think cheese is made from plants and nearly one in 10 secondary pupils thinks tomatoes grow under ground, according to a new survey.
The poll for the British Nutrition Foundation (BNF) also revealed confusion about the source of staples such as pasta and bread among younger pupils, with about a third of five-to -eight-year-olds believing that they are made from meat.
Some 27,500 five-to-16-year-olds were questioned last month for the poll.
Some 19 per cent of this age group did not realise that potatoes grew under ground, with 10 per cent thinking they grew on bushes or trees.
The charity says the figures prove the need for better teaching about cooking and healthy eating.
The researchers also reported "that an alarming number of children do not eat breakfast each morning". The numbers skipping breakfast also increase with age, according to the study.
Asked whether they had eaten breakfast that morning, some eight per cent of primary children said they had not. This increased to nearly a quarter (24 per cent) of 11-to-14-year- olds and almost a third (32 per cent) of 14-to-16-year-olds.
Roy Ballam, education programme manager at BNF called for a national framework and guidance for food and nutrition education across the UK, "especially at a time when levels of childhood obesity are soaring".
A spokesman for England's Department for Education said: "We want to encourage children to develop a love of food, cooking and healthy eating that will stay with them as they grow up."
He added that its curriculum reforms would make food and nutrition compulsory for eight-to-14-year-olds, while the new design and technology curriculum would allow teachers to explain food production.
