3 years & up. Keep up with the time using this brightly colored Mega Sand Timer Set for Classroom Activities Indoors and Outdoors. This classic hourglass timer is the perfect tool to help children visualize time from seconds to 10 minutes! Use these exciting times for science experiments, time management, and other timed games. These sand timers are time-tested and made of durable plastic. Timers come with matching colored sand. Each timer measures 3.25"L x 6.375"W.