When the kids are ready to move beyond the tidy fractions of an hour, you can start adding on a few odd minutes here or there. Have them start by adding single minutes to multiples of five-minutes.
First demonstrate that there are five-minutes between each number on the clock. Most clocks have lines for this purpose.
Next, let's say the clock reads 7:36. The kids can tell that it's after 7:00, after 7:30, and close to 7:35, and since the minute hand points to the minute mark just past the 35, the kids should be able to figure out that the time is 7:36.
Note: It may be easier for kids to subtract single minutes from (not add them to) the multiples of five-minutes on a clock. For example, 3:49 is only 1 minute shy of 3:50. Some kids will prefer to subtract one-minute from 3:50 while others will prefer to add four-minutes to 3:45.
It's more fun if you can use an older sibling to help practice. Partner them up for this exercise: Have one partner choose a time that ends with a five or a zero (such as 6:30 or 7:25) and write it down. Have the other partner choose a number between one and four and write it down. Now let the child try to add the smaller number to, and then subtract it from, the original time the first partner chose. Check their math and then have them draw clocks corresponding to both answers.
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Stop by tomorrow for the last step in Teaching Kids to Tell Time.