Boring break times and poorly designed playgrounds are partly to blame for school bullying, a charity claims.
Many parents valued their own playground memories
A poll of 1,146 children suggests one in four had been bullied in the playground while one in six got bored, but almost all (93%) enjoyed playtimes.
The school grounds charity, Learning Through Landscapes, says children engage in bullying and negative behaviour because they are bored.
One solution would be to engage them in more stimulating play, it added.
Chief executive of the charity, Catherine Andrews, says: "Whilst it is said that children will play anywhere, the quality of the experience is undoubtedly related to the quality of the environment.
"School grounds have the potential to offer a potentially limitless range of experiences and opportunities. However the design of the grounds will determine what children do in them."
The research conducted for one of the charity's supporters, the Royal Bank of Scotland, suggested bullying was parents' top concern.
Some 51% of the 1,102 parents polled saying they feared this for their children the most.
One in five said they were most concerned about their child's welfare in the playground, while 13% said they were more worried about dangers outside the school gate.
A quarter of parents said they thought their child's playground facilities needed to be significantly improved.
'Good old fashion fun'
And 83% agreed that the school playground had a lasting influence on their own personal development.
One in five parents said there was a lack of sporting facilities to keep children active and engaged.
And a quarter wanted to see more seating areas which encouraged social interaction.
But parents also said that schools do not allow children to experience "good old fashioned fun" in the playground, with 57% agreeing that children were "too wrapped up in cotton wool".
However, some 93% of children said they enjoyed playtime. Just over half (52%) enjoyed chatting with friends and just over a third (36%) liked to participate in various sports.
A spokeswoman for the Department for Children, Schools and Families said it supported the need for the need for attractive and stimulating school grounds, which was why it had produced a number of design guides.
On playground bullying, she added: "Bullying has no place in our schools. We are determined to stamp it out in all its forms."
The results of the research were released as the Royal Bank of Scotland launched its Dream Playgrounds competition offering money to transform school playgrounds.
People are invited to nominate schools for the chance of winning a £10,000 make-over.
The survey was done by Tickbox.net, who asked 1,146 UK children aged between six and 11 and 1,102 parents with children in this age group.