Many of the nation's children believe fish fingers are made of chicken, cheese comes from plants and tomatoes grow underground, according to a new poll.
The survey suggests confusion among youngsters on where their food comes from and whether it counts as healthy and nutritious.
Nearly a third of five to seven-year-olds thought that cheese came from a plant, not an animal, while one in four older primary school pupils thought the same.
In addition, just over one in five of the infants, and 13% of the older primary group believed that animals provide us with pasta.
There was also uncertainty about other foods, with 22% of five to seven-year-olds saying prawns come from plants and 20% suggesting that chips are made of animals.
Among the eight to 11-year-olds questioned as part of the British Nutrition Foundation (BNF) poll for its Healthy Eating Week, there was less slightly confusion, although 10% thought that bread came from animals.
The majority of children knew that fish fingers are usually made from haddock or cod but 18% of the younger pupils thought they were made of chicken, along with 6% of the older group.
Around one in 10 of 11-14-year-olds and a similar proportion of 14-16-year-olds thought that tomatoes grow underground, with 40% of the younger age group saying they grow on a vine and 22% saying on a bush (49% and 18% respectively for the older age range).
Some 11% of both 11-14-year-olds and 14-16-year-olds thought that fruit pastilles counted towards their five-a-day, while 27% of the younger group and 26% of the older range thought that they could include strawberry jam as part of their daily fruit and veg.
The findings of the survey, which polled more than 5,000 children, did show that 31% of 11-14-year-olds and 28% of 14-16-year-olds say that they know lots about healthy eating and try to follow it, while almost half of the younger group and 48% of the older children say they know lots but either do not follow it or do not always follow it.
Roy Ballam, BNF managing director and head of education said: "Schools and families can and should successfully work together to, in turn, educate children and then motivate them in their endeavours to make healthier choices.
"Furthermore, the links between physical activity, health and diet should be frequently highlighted by the Government's programmes."