Cheese comes from plants and fish fingers are made of chicken, according to a significant number of children questioned on their knowledge of where food comes from.
The British Nutrition Foundation (BNF) included more than 27,500 children in the research and found that nearly a third (29 per cent) of primary school children think that cheese comes from plants, and nearly one in five (18 per cent) primary school children said that fish fingers comes from chicken.
The survey also found that one in 10 secondary school children believe that tomatoes grow under the ground.
The largest of its kind, the study was conducted as part of the BNF's Healthy Eating Week, which is launched today by The Princess Royal.
More than 3,000 schools are participating in the week-long event, during which over 1.2 million children will learn about healthy eating, cooking and where food come from.
Roy Ballam, education programme manager at the BNF, said the high numbers of schools taking part shows there is an understanding of how important it is to encourage healthy eating.
"Schools throughout the UK require a national framework and guidance for food and nutrition education to support the learning needs of children and young people, especially at a time when levels of childhood obesity are soaring.
"Through Healthy Eating Week, we hope to start the process of re-engaging children with the origins of food, nutrition and cooking, so that they grow up with a fuller understanding of how food reaches them and what a healthy diet and lifestyle consists of.
"The fact that so many schools in England, Northern Ireland, Scotland and Wales have registered to participate in the Week demonstrates their understanding of how important healthy eating is and their commitment to giving children a solid grounding from which to create healthy lives for themselves," he said.
Over three quarters (77 per cent) of primary school children and nearly nine out of every 10 (88 per cent) secondary school pupils know that people should consume five or more portions of fruit and vegetables each day.
However, 67 per cent of primary school children and 81 per cent of secondary school pupils reported eating four or less portions of fruit and vegetables daily, while two in every five children at secondary school did not think that frozen fruit and vegetables count towards their five a day.
The research also shows that a significant number of children do not eat breakfast each morning, which increases with the age of the children.
On the day of the survey, 8 per cent of primary school children said they had not eaten breakfast that morning, and this increased to nearly a quarter (24 per cent) in 11-14-year-olds, and to over a third (32 per cent) of 14-16-year-olds.
When questioned on the more general point as to whether they have breakfast each morning, 6 per cent of primary school children, 19 per cent of 11-14-year-olds and a quarter of 14-16 year olds reported not eating breakfast every day.
The BNF research also looked at reported home cooking behaviour and shows that 17 per cent of primary school children and 19 per cent of secondary school children cook at home either every day or once a week.
However, 9 per cent of children at primary school and 11 per cent of children at secondary school said they never cook at home.
84 per cent of primary school children and nearly three quarters (73 per cent) of secondary school children would like to cook more and an average of 85 per cent of children across all age groups said they enjoy cooking.
Mr Ballam added: "Through this survey one in five (21 per cent) primary school children and 18 per cent of secondary school pupils told us that they have never visited a farm.
"This may go part way to explaining why over a third (34 per cent) of five to eight-year-olds and 17 per cent of eight to 11-year-olds believe that pasta comes from animals."