Climbing trees - a mate of mine, aged 11, fell about fifteen feet high up an elm, I think it was as to species. Fortunately, he caught a branch on the way down.
No different to adults though. I was working in my (corner) office in Hong Kong, 16th floor of a 17 floor building, bamboo scaffolding having been put on to it so as to screen the windows with a reflective sheet to reduce the impact of the sun. Looked up to see this Chinese guy falling past the window - he managed to grab onto the bamboo on the 9th floor....a close thing indeed.