Big Ideas: Time can be measured. Time is the duration of an event from its beginning to its end. This lesson builds on students’ work with telling and writing time to the nearest 5 minutes. The task uses a number line diagram (or clock number line) to locate, plot, and read time to the exact minute. To do this, students will use their understanding that the numerals and marks on a clock represent specific increments of time. The mathematical concept in this lesson builds towards students’ future work with solving word problems involving elapsed time. Vocabulary: elapsed time, hour, minute, second, digital clock, analog clock Special Materials: Clock manipulatives (optional) Copies of clock number lines for each student (optional)