GraviTrax Starter Set

Ages 8 and up A marble run that behaves like an engineering problem. Children stack height tiles, plan curves and drops across the base plates and then find out, ball by ball, whether the design has enough height and speed to finish the course. Every failed run is a lesson in gravity and momentum that a child diagnoses and fixes without being told. The Starter Set lists at about $75 and holds weeks of builds on its own, and the system's long line of expansions keeps it growing for years. The one warning for gift buyers is that once a child is hooked, the add-on sets become the next five birthday requests.