Pendulum Play is excellent for learning cause and effect, physics, spatial reasoning, experimenting with weight and size, language, vocabulary and teaches kids how to work together. I made this pendulum out of PVC pipes, string and tennis balls. After the initial excitement of knocking blocks down, the kids began experimenting with the the limitations of the ball and began building their towers more strategically. This is a great way for kids to learn through play! Very easy set up!