Homework Trail

Clocks and Time · Grades 3–5

How to Calculate Elapsed Time

Elapsed time is the amount of time between a start and an end. Counting forward in sensible jumps makes the interval easier to see.

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What children need to know first

  1. A time interval can cross an hour boundary; minutes do not restart the elapsed-time count.
  2. One hour is 60 minutes.

Step-by-step explanation

  1. Write the start time and end time.
  2. Count forward from the start to a nearby hour or half hour.
  3. Continue counting in jumps until the end time.
  4. Add the jumps to get the total elapsed time.

Worked examples

From 2:40 to 3:15

2:40 → 3:00 is 20 minutes; 3:00 → 3:15 is 15 minutes.

Answer: 35 minutes 20 + 15 = 35 minutes passed.

From 9:10 to 10:25

9:10 → 10:10 is 1 hour; 10:10 → 10:25 is 15 minutes.

Answer: 1 hour 15 minutes The jumps together span 75 minutes.

036912four jumps of 3
Count forward in jumps, then add the intervals.

Common mistakes and how to fix them

  1. Subtracting minutes without crossing the hour correctly. Count forward across 60 minutes instead.
  2. Forgetting a jump in the middle. Record each interval above the timeline and add them.

Parent teaching tips

  1. Use a clock face or timeline and let the child move a marker forward.
  2. Have the child estimate whether the answer should be less than or greater than an hour.

Independent practice

  1. How much time passes from 1:35 to 2:05?
  2. How much time passes from 8:20 to 9:50?

Practice answers

  1. 30 minutes
  2. 1 hour 30 minutes

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Open the matching Grades 3–5 activity for Elapsed Time. You can print its worksheet with questions only or an answer key.

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