Elapsed Time - Differentiated Reteach, Review

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SWBAT review and apply strategies for telling time to the minute/elapsed time while solving word problems.umber line.

Big Idea

Students benefit from cyclical review of multi-step skills.

Vocabulary Review

5 minutes

Review the following words with students, as needed, using straightforward teacher generated examples. Realia (objects) are particularly useful when working with ELL students, so having a demonstration clock on hand is recommended.

hour, minute, elapsed, starting time, ending time, schedule, quarter hour, half hour, interval

Then ask students to come up with their own meaningful sentences for the words. Working with a partner encourages specific vocabulary and contextually rich sentences, and I circulate to check in on that expectation.

Mini Pre-Assessment

15 minutes

The purpose of this Time Cycle 2 Mini Pre-Assessment is to refresh student thinking about time and also to help them continue to develop their self-evaluation skills.  The teacher will give no more than 15 minutes for this assessment, as it is intended as a diagnostic.  Unless students are at complete mastery, have them show their work so you can make meaning of their mistakes and celebrate their strengths.  If you would like to project the problems and have students number a blank piece of paper to complete this pre-assessment, here is a shorter version of the problems.


15 minutes

A common mistake made by students experiencing difficulty accurately calculating elapsed time is that they skip steps.  In this mini-lesson the teacher presents, step-by-step, using a number line to calculate elapsed time.

Strategy 1 (insert ShowMe)

  1. Put the known time or times on the number line.
  2. Add or subtract the maximum number of hours possible and record that amount above the “jump(s) taken on the number line.
  3. From that point, add on the remaining minutes.  

Review the word problem stories from the test.  Demonstrate the first problem in each pair and have the students work through the second example on their whiteboard or the back of their pre-assessment paper, and then check it together.  Emphasize to students that this is not a grade, but a chance for them to determine for themselves which skill (hour, 1/2 hour, 10 min, 5 min, 1 min) related to elapsed time intervals will be their study choice for today.

Active Engagement

40 minutes

I allow students to place themselves into what they feel is the appropriately leveled group and place versions of these problems on the board.  They wrote their choice number (a,b,c, or d) and then number the problems on blank paper.  All students need to draw out is the number line.  An alternative is to use the pages as study guides, which helps if you don't have the time or space to write all of this up on the board.  

I explain to students that I expect to hear them using specific mathematical language as I walk the room, and that at the end of today's activity they would need to be able to explain the steps of the process to a classmate or to me.

I provide a few sentence stem examples, such as:

"I know that the first step in this problem is to put my starting time on the number line."

"I see that the elapsed time is 5 hours and 45 minutes, so my second step will be to count ahead 5 hours from my starting time of 9:30.  I will mark the 5 hour point, and then count on by fives to add the 45 minutes."

Elapsed Time Practice Hr Half Hr Choice A

Elapsed Time Practice Half Hr Ten Min Choice B

Elapsed Time Practice Ten Min Five min Choice C

Elapsed Time Practice 5 Min 1 Min Choice D


5 minutes

At the conclusion of this lesson there are two different ways to close.  I call on a few random students to explain the steps they take to solve an example problem (from their level) or I have them pair with a partner to explain their steps and then the partner points out if anything was unclear or out of order.  Then they switch roles and repeat the process.  For this to be meaningful, it is essential that I circulate and monitor the conversations, supporting ELL students with sentence stems and key vocabulary when necessary.