The teaching of time has often been misconstrued as the “telling of time.” Being able to read and recite time from the face of the clock does not mean that children understand time, the passing of it, or the mathematics involved in the measuring of it. To compare durations, standard units are needed like hours, minutes, and seconds and these can be decomposed, added, seen as fractional pieces of a larger unit (for example, half an hour), and exchanged—for example, 30 minutes can be exchanged for half an hour. This unit is crafted and sequenced carefully to foster those understandings. It is part of the Contexts for Learning Mathematics series (CFLM), an elementary curriculum series used by many schools across the U.S. and around the world. It is designed to align with the U.S. Common Core objectives for grade 1. - from Amzon