Over time, public playgrounds have become safer: metal apparatuses were replaced by wood and then plastic, concrete or gravel was replaced by grass and then recycled rubber pellets, and anything that could conceivably present a risk was removed. Kids crave thrills, independence, creativity, and a feeling of accomplishment, which is why you take your kid to a playground and find them climbing the fence instead of the plastic ladder. “Adventure playgrounds” are different. They have building materials and tools for children to design their own equipment. They allow children to take risks while still in a controlled environment, which teaches them how to judge risks. And kids have way more fun.