Help students visualize, calculate and understand elapsed time with this linear color-coded ruler. To determine elapsed time, students place a sliding marker at both start and end times, then count the time in between the markers. Features red AM hours, green PM hours and blue minute increments. Markings offer flexibility of 5- to 60-minute intervals. Plastic ruler measures 24"L x 2 1/2" W and folds in half for convenient storage. Activity Guide included.