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Solve Word Problems Involving Time Intervals

Students solve word problems involving elapsed time, start time, and end time using addition and subtraction. Problems may include converting between hours, minutes, and seconds, and using number lines or timelines as tools.

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Solve Word Problems Involving Time Intervals

Grade 4 · Measurement Word Problems · question 1 of 3

0 of 20

20 rungs. A star at the top.

Kofi rakes leaves for 28 minutes and then bags them for 19 minutes. How many minutes does he spend on the leaves?

How it is taught

0:00 of 3:48

Elapsed time is the gap from start to end.

A timeline helps you hop by hours, then minutes.

Read it: Count up to the hour

A game starts at 3:20 and ends at 4:05. Count up: 3:20 to 4:00 is 40 min, then 4:00 to 4:05 is 5 min. The game is 45 min long.

  1. Put the start time on the line.
  2. Jump to the next hour, then whole hours, then the minutes left.
  3. Add the jumps: that is the time taken.

An hour is 60 min, not 100, so times do not take away like plain numbers.

Jumping to the hour first keeps every jump easy to add.

An end time is the start counted on, and a start time is the end counted back.

Count up from the start to the end: to the hour, then on. Add the jumps.

Getting 85 min by taking the times away as if they were plain numbers.

An hour has 60 min. 3:20 to 4:00 is 40 min, then 5 min more to 4:05: 45 min.

Lila reads from 4:00 PM to 5:30 PM. How many minutes? — 90. 4:00 PM to 5:00 PM is 1 hour, 5:00 PM to 5:30 PM is 30 minutes: 60 + 30 = 90 minutes.

10:15 AM to 12:05 PM — how long?

A soccer game started at ten fifteen in the morning and ended at five minutes past twelve. How long did it last?

Draw a timeline. Put the start on the left and the end on the right, then find the gap between them.

Notice something first: this game crosses noon. Morning turns into afternoon, so A M becomes P M — but the counting just keeps going. Noon is not a restart.

Hop by a friendly amount. From ten fifteen, one whole hour lands on eleven fifteen.

From eleven fifteen to twelve oh five is fifty more minutes. Two hops, and we have reached the end.

Add the hops together: one hour plus fifty minutes is one hour and fifty minutes.

Careful — one hour fifty minutes is not one point five zero hours. Time is not base ten. An hour holds sixty minutes, so fifty minutes is most of an hour, not half of one.

How long was the game?Start 10:15 AM — End 12:05 PMStart 10:15 AM — End 12:05 PM10:1512:0512:00 noonAM becomes PM — the clock does not restart the count11:15+1 hour+50 min1 hr+50 min=1 hr 50 minNOT 1.50 hoursan hour has 60 minutes, not 100ANSWER1 hr50 minthe soccer game
Grade 4 · A soccer game from 10:15 AM to 12:05 PM

The game lasted one hour and fifty minutes. Mark what you know on a timeline, hop in friendly pieces, and add the hops.

What you see

While they climb, your page writes one true line to ask about tonight, and a short note each Sunday.

MayaGrade 3 · Mathematics
Did you know?

A chessboard has 64 squares — share them out between the 8 rows and each row holds exactly 8.

Today’s goal
1 star — one skill mastered, every rung of its ladder climbed
Climbing now
Divide within 100

An example student.

MayaGrade 3 · Mathematics

Maya earned 2 stars this week — Interpret multiplication as equal groups, which took 6 answers over 3 days before its star landed 3 days ago and Multiply by 6, 7, 8 and 9. Next up: Divide within 100.

An example week.

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