Math Mammoth Clock is a worktext (containing both the instruction and the exercises) that covers time-related topics for first through fourth grade level of school. The book covers telling time with an analog clock, figuring out time intervals (elapsed time), and using the calendar, all in one book. The lessons about telling time are divided into the grade-levels this way: the first five lessons (up till the lesson “Review 1”) are first grade material; the next four lessons (up till the lesson “How Many Hours Pass?”) are for second grade, and the lessons up till “Elapsed Time 4” are for third grade. Then follow the lessons on calendar, covering material for the first three grade levels. Lastly the book has lessons on elapsed time and the 24-hour clock, which are meant for fourth grade. In several lessons, you will need a practice clock, such as an alarm clock, where the child can turn the clock hands. Telling time is a skill that will be used in everyday situations, so this topic (fortunately) is one that children also learn by experience, and do not easily forget once learned. However, reading an analog clock is not nearly as common today as it used to be, so that skill may need review. Hanging an analog wall clock at home or in the classroom can help. You can also practice both telling time and elapsed time at the Math Mammoth Practice website. The answer key is appended to the book.