One of the math concepts that teens often struggle with is figuring out “elapsed time” — such as how much time is between two times, or what time it will be in so many hours and minutes.

I don’t remember where I picked up this idea, but I’ve been using it lately and it works great! So, I’ll share it here for you to try.

Start by drawing a big “Z” on the paper or whiteboard (see the photo above). On the top left, write the starting time. In this example, the start time is 8:45 a.m.

Now figure out what the next “o’clock” time would be, in other words the next hour, and write that on the upper right-hand corner of the “Z”. In this example, that is the 9:00 a.m.

The next step is to write the “o’clock” (hour) time just before the desired end time on the lower left corner of the “Z”. In this example, that is 1:00 p.m.

The end of the Z is the final time, which in this case is 1:25 p.m.

Now figure out how many minutes are between the starting time and the first corner time. There are 15 minutes between 8:45 and 9:00, so we wrote that on the top line.

Then count the hours from the one corner to the other on the “Z” — so from 9:00 to 1:00 in this example is 4 hours.

Almost done . . . the minutes on the last line are easy to figure out. 25 minutes in this case.

Finally, add up the minutes and put with the hours! 4 hrs and 40 minutes for this problem.

**Now try your hand at it! **Draw a “Z” and put the start and finish times in:

- Time between 10:35 p.m. and 5:27 a.m.
- Start with 10:50 a.m. and figure out what time is will be in 5 hours and 30 minutes
- If the school day starts at 8:30 a.m. and ends at 2:45 p.m. how long is the school day?

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