Teenage schoolchildren think oats grow on trees and bacon comes from sheep, a survey has shown.
Many children and young adults also believe eggs are a key ingredient in bread, the researchers said.
The survey shows 26% of children believe bacon comes from sheep, 29% think oats grow on trees, while 17% of both children and adults under the age of 30 believe eggs are a core ingredient in bread.
Peter Kendall, president of the National Farmers' Union, said: "The results show how important it is to teach the adults of tomorrow about the food they eat.
"Everyone should know where primary foods like cereals are grown and the role they play as part of a healthy, balanced diet.
"It is critical that children and adults alike understand more about their food, and the role British Farmers play in producing it."
The survey, conducted on behalf of Home Grown Cereals Authority (HGCA) in the build up to the Farmhouse Breakfast Week awareness campaign, concluded older generations know "much more" about food.
The majority of over-40s questioned know where oats come from and that bread is made from flour, water and yeast.
The survey was conducted online by OnePoll and YoungPoll during November, prompting almost 3,000 replies.