This unique, write-on wipe-off tool allows students to measure time in a number line format where they can visually see where the time goes. Think of this time tool as an analog clock unwound into a 24-hour format with A.M. marked in red and P.M. marked in blue. Hours are divided into five minute increments marked with dashes and 15 minute increments are also noted. Student version features interlocking ends for elapsed time questions from P.M. to A.M. Great for elapsed time and duration of time questions. Classroom set includes one demonstration ruler, one overhead ruler and 30 student rulers.