Teachers fear traditional playground games like British bulldog and conkers are disappearing from many of England's schools, a survey suggests.
More than a quarter (29%) of the 653 school staff surveyed by the Association of Teachers and Lecturers (ATL) said chasing game British bulldog had been banned from their school.
Some 14% said pupils were banned from playing conkers and 9% said leapfrog.
Most (57%) said they felt schools were becoming increasingly risk averse.
The research was published at the ATL teaching union's annual conference in Liverpool on Tuesday.
And overall 15% of teachers, lecturers, support staff and school leaders said that fewer playground games and sports activities were played at their school than three years ago.
The key reasons for the decline were fewer staff on hand to supervise activities, reduced funding and concerns over pupil safety.
One secondary school teacher said the game, bulldog, was banned at her school "because of the number of broken bones it generates!"
And a primary school teacher said: "Apparently the main problem with conkers is that nut allergy sufferers are increasingly allergic to them."
Teachers were also questioned about changes in attitude towards risk. Some 57% of staff said there was a growing trend towards risk aversion in schools.
And of the 383 staff who thought schools were more risk adverse, 90% said it constrained activities both in and out of school.
Some 84% think it limits the curriculum, while 83% believe risk aversion puts a brake on pupils' preparation for life.
A deputy head teacher at a primary school in Cleveland said: "All staff recognise the need to keep children safe, but not all recognise that children still need to take measured risks to develop real life skills."
A teacher at the Froebel Small School in East Sussex said it tried to help children learn to be safe.
"Children are allowed to explore their physical limits and learn to negotiate physical tasks at their own pace. Staff have clear guidelines and children have clear boundaries," the teacher added.
Another secondary school teacher, from Wales, said: "Pupils need to learn their own limitations, which they can't do if they don't encounter risk."
And there continues to be fears that school trips could end in teachers or schools being sued, should something go wrong.
'Mud and love'
The majority of staff think school trips and activities are very important, with 92% of those surveyed saying they enhanced learning and support the curriculum.
Some schools already have a relaxed attitude towards risk. A teacher at a primary school in England told how its children go on weekly nature walks and end up being taught how to make a campfire and cook on it.
"We also spend the day in the woods around a fire pretending to be Anglo-Saxons. Mud and love is our motto. I think we are unique!"
ATL general secretary, Mary Bousted, said: "Teachers, lecturers, support staff and school leaders all recognise that children need to be safe, however, without encountering risk it is difficult for them to learn their own limitations."