According to research by the Children's Society charity, more than half of the 2.2 million children living in poverty in England miss out on a free school meal every day.
Around 700,000 of these are not entitled to one, and a further 500,000 do not take them up because a fear of being stigmatised, the charity said.
Matthew Reed, chief executive of The Children's Society, said:
– Matthew Reed, chief executive of The Children's Society
This report sets out shocking evidence of just how much hardship teachers up and down the country are witnessing in classrooms day in, day out.
Something is going badly wrong when teachers themselves are having to feed children.
Every child in poverty should be given a free school meal. Free school meals are key to moving children out of poverty and vital to helping them flourish.
New research by the Children's Society charity has found that two thirds (66%) of school staff say that teachers are providing pupils with food or money for meals if they turn up for lessons hungry.
One teacher told researchers: "They come to school and have not had breakfast. They take toast that they have not paid for because they are so hungry."
Another teacher said: "Last month I found two girls sat on the toilet floor sharing one's packed lunch because the other girl had no lunch money."
Children are still turning up to school hungry and skipping meals at lunchtime because they cannot afford to eat, according to new research.
In one case, a teacher found two girls sharing a packed lunch in the school toilets because one had no money for food, according to a report by the Children's Society charity.
The study, based on a survey of around 570 teachers, reveals serious concerns among school staff about the levels of hunger among pupils.
Almost three in four (72%) of the teachers surveyed said they have seen pupils coming into school with no lunch and no way to pay for one.