As a child my favourite climbing frame was a large oak tree that had fallen over near my nursery. We would climb onto the branches and jump up and down. There was an element of risk but the physical benefits and the fun we had outweighed the risk. As children we instinctively sought out this kind of large muscle play and in time became more skilled and daring.
Many settings try to remove risk, but life does not give us that option. Children sometimes fall down as they run around, but a sedentary lifestyle may have greater health risks than a barked knee or a scraped elbow. Balancing across a plank is a risk that children are able to understand and weigh-up themselves, as is building a house with hollow blocks. Even the Health and Safety Executive agrees that “the goal is not to eliminate risk, but to weigh up the risks and benefits”. Here is the link to their statement. This is a great topic for staff discussion and you may want copies for parents.