This is a wonderful STEM toy. This is our second set of K'Nex and we have been trying them out, really for the first time. My boys love them. This set is recommended for boys 9 and up, and I would stick to that recommendation because it can be challenging for children younger than that. If you have a child who is already familiar with K'Nex and understands a bit more about engineering with them, then this is right up their alley. All the directions are in step by step pictures, so that the kids can follow along with it easily. My son did need some assistance putting his together on a few parts, but for the most part, he put it together himself. It took him a while to figure it all out on his own, but it was his project and he loved doing it. He did have difficulty with the chain that makes the roller coaster move on the actual ride, we are still trying to figure out the best way to adjust to make that work properly. But he is engaged and thinking more in depth, how to solve his engineering problem. I love these, they are great for improving problem solving skill and critical thinking.