Geared, color-coded clock lets you both demonstrate elapsed time concepts and assess student understanding. To begin, use the clock hands to set the start time. Then, move the knobs on the back to clear the digital display. Move the hands to the end time, and the digital display will show the elapsed time. In small groups, students can close the digital display windows, move the hands from start to end time, then open the windows to check their answers. Geared clock displays time in 1-minute increments and measures 15"L x 15 1/2" H.