You will learn
- Find elapsed time.
- Add and subtract hours and minutes.
- Convert between hours and minutes.
- Solve time problems.
Version 0.2 · expanded edition · built from cited public sources Content is based on the official frameworks and sources listed under Sources and standards. No official endorsement is claimed. Written in the style of common primary school assessments. No exam result is promised.
Student lesson
- Elapsed time is how much time has passed.
- Count up to the next hour, then the minutes.
- Regroup minutes into hours (60 minutes = 1 hour).
- Use a number line to check.
Words to know
Time that has passed.
The time between two times.
Morning/afternoon.
60 seconds.
1. Discover: a school day
School starts at 8:15 a.m. and closes at 1:05 p.m. How long is that?
2. Understand: elapsed time
- 2:45 to 5:20: 2:45 to 5:00 is 2 h 15 min, plus 20 min = 2 h 35 min.
- 8:15 a.m. to 1:05 p.m.: to 12:00 is 3 h 45 min, plus 1 h 05 min = 4 h 50 min.
- 135 minutes = 2 h 15 min.
- 3 h 40 min + 1 h 35 min = 5 h 15 min.
Idea 1: Elapsed
9:10 to 11:50: 9:10 to 11:10 is 2 h, then 40 min more. Total 2 h 40 min.
Idea 2: Add
1 h 20 min + 2 h 45 min = 3 h 65 min = 4 h 5 min. 180 min = 3 hours.
Idea 3: Across noon
10:30 a.m. to 2:15 p.m.: 10:30 to 2:30 is 4 h, minus 15 min, so 3 h 45 min.
Why 60? There are 60 minutes in an hour, not 100.
3. Worked examples
Example 1 (I show you): Elapsed
9:10 to 11:50
- 2 h and 40 min.
Answer: 2 h 40 min
Example 2 (We do it together): Add
1 h 20 min + 2 h 45 min
- 65 min = 1 h 5 min.
Answer: 4 h 5 min
Example 3 (You try): Convert
180 minutes
Show the steps and answer
- 180 ÷ 60.
Answer: 3 hours
Did you know?
The 24-hour clock avoids a.m. and p.m.
Why this matters
Time problems help us plan our day and journeys.
4. Explore: elapsed
You need a clock.
- Write 2:45 and 5:20.
- Count to 5:00.
- Add 20 min.
- Write the interval.
Think about it: what did you notice?
2 h 35 min.
5. Practise
Say it in a sentence
Use these starters when you talk about the lesson. Say them out loud.
- I count on to ___.
- The elapsed time is ___ h ___ min.
- ___ min = ___ h ___ min.
- The end time is ___.
Guided practice
Question 1. 2:45 to 5:20?
2 h 35 min.
Question 2. 135 min in hours?
2 h 15 min.
Question 3. 3 h 40 + 1 h 35?
5 h 15.
Independent practice
Level 1: Start
- 9:10 to 11:50
- 1 h 20 + 2 h 45
- 180 min in hours
- 10:30 a.m. to 2:15 p.m.
- 4 h 10 − 1 h 30
Level 2: Grow
- 8:00 to 10:35
- 90 minutes in hours
- 2 h 15 min + 1 h 50 min
Level 3: Stretch
- 1:45 p.m. to 6:10 p.m.
- 6 h 5 min − 2 h 40 min
- Ben says 2 h 45 min + 1 h 30 min = 3 h 75 min. What is wrong?
Answers are in the answer key below. Try first, then check.
6. Apply: everyday mathematics
A film starts at 2:45 and ends at 5:20. How long is it?
Show a sample answer
2 h 35 min.
Another one. Ife starts homework at 4:20 p.m. and finishes at 6:05 p.m. How long did it take?
Show a sample answer
4:20 to 6:20 is 2 h, minus 15 min, so 1 h 45 min.
7. Common mistakes
Fix: 60 minutes make an hour.
Fix: 60 minutes make 1 hour.
Fix: Change 60 minutes to 1 hour.
8. Lesson summary and revision card
- I can find elapsed time.
- I can add and subtract hours and minutes.
- I can convert between hours and minutes.
- I can solve time problems.
9. Check and master
Answer all 14 questions. You will see feedback after each one.
Your result appears here after you answer every question.
10. Key takeaways
- Count on to the hour.
- 60 minutes per hour.
- Regroup carefully.
11. Next lesson
Next lesson: Measurement applications. Keep going with the next idea in this course.
Exam practice
These questions are written in the style of common school and international primary assessments. Try them on your own, without looking back. Then check your answers in the marking guide. The marks are shown in brackets.
- Find the time from 9:10 to 11:50. [2 marks]
- Find 1 h 20 min + 2 h 45 min. [3 marks]
- Change 180 minutes to hours. [1 mark]
- Find the time from 10:30 a.m. to 2:15 p.m. [3 marks]
- Ali says 4 h 10 min − 1 h 30 min = 3 h 20 min. Is he right? Explain. [3 marks]
Total: 12 marks.
Marking guide and model answers
- 9:10 to 11:10 is 2 h [1]; 2 h 40 min [1]
- 3 h 65 min [1]; 65 min = 1 h 5 min [1]; 4 h 5 min [1]
- 3 hours [1]
- 10:30 to 2:30 is 4 h [1]; minus 15 min [1]; 3 h 45 min [1]
- No [1]. Regroup: 3 h 70 min [1]. 2 h 40 min [1].
Score guide: 11 to 12 = secure. 8 to 10 = nearly there, revise the parts you missed. Under 8 = work through the lesson again with a grown-up.
Printable worksheet
- 9:10 to 11:50
- 1 h 20 + 2 h 45
- 180 min
- 10:30 a.m. to 2:15 p.m.
- 4 h 10 − 1 h 30
- 2:45 to 5:20 is
- 135 minutes =
- 3 h 40 min + 1 h 35 min =
- 9:10 to 11:50 is
- 180 minutes =
Homework
Record the time you start and finish three activities.
Answer key and marking scheme
| Question | Expected response | Marks |
|---|---|---|
| 9:10 to 11:50 | 2 h 40 min | 2 |
| 1 h 20 + 2 h 45 | 4 h 5 min | 2 |
| 180 min | 3 h | 2 |
| 10:30 a.m. to 2:15 p.m. | 3 h 45 min | 2 |
| 4 h 10 − 1 h 30 | 2 h 40 min | 2 |
| Total | 10 |
Practice answers: Worksheet: 1 2 h 40 min; 2 4 h 5 min; 3 3 h; 4 3 h 45 min; 5 2 h 40 min.
Quiz answers: 1 A, 2 B, 3 C, 4 A, 5 B, 6 A, 7 B, 8 C, 9 A, 10 B, 11 C, 12 A, Challenge 1 C, Challenge 2 C.
Extra worksheet answers (items 6 onward): 6 2 h 35 min; 7 2 h 15 min; 8 5 h 15 min; 9 2 h 40 min; 10 3 hours.
Independent practice answers. Level 1: 1 2 h 40 min; 2 4 h 5 min; 3 3 hours; 4 3 h 45 min; 5 2 h 40 min. Level 2: 1 2 h 35 min; 2 1 h 30 min; 3 4 h 5 min. Level 3: 1 4 h 25 min; 2 3 h 25 min; 3 75 min = 1 h 15 min, so the total is 4 h 15 min..
Mastery and remediation
| Objective | Bronze (Developing) | Silver (Proficient) | Gold (Advanced) |
|---|---|---|---|
| O1 Find elapsed time | Shows this with help from an adult or a picture | Does this independently and explains how they know | Explains it clearly and uses it in a new situation |
| O2 Add and subtract hours and minutes | Shows this with help from an adult or a picture | Does this independently and explains how they know | Explains it clearly and uses it in a new situation |
| O3 Convert between hours and minutes | Shows this with help from an adult or a picture | Does this independently and explains how they know | Explains it clearly and uses it in a new situation |
| O4 Solve time problems | Shows this with help from an adult or a picture | Does this independently and explains how they know | Explains it clearly and uses it in a new situation |
Courseversity badge thresholds (overall quiz score): Gold = 90–100%; Silver = 80–89.9%; Bronze = 70–79.9%. A badge is never a full record of progress.
If a learner struggles
- Find the misconception: Using 100 minutes in an hour. 60 minutes make an hour.
- Explain another way: use real objects first, then pictures.
- Show a simpler example: Practise reading clocks.
- Guided practice: work through one example together and let the learner try the next one.
- Reassess: use the quiz again or the worksheet.
- Move on when the learner shows Silver-level evidence independently.
For parents and guardians
In this lesson your child finds elapsed time and adds and subtracts hours and minutes. You do not need to be good at mathematics to help.
- Time journeys and chores.
- Ask: how many minutes to the next hour?
- Use a clock face to count on.
- Ask “how do you know?” after each answer, and listen.
- Praise effort, not only right answers. Mistakes are how we learn.
- Ten to fifteen minutes a day is better than one long session.
Teacher package
1–5. Objectives, prerequisites, materials, preparation, duration
Lesson objectives. Learners will: find elapsed time; add and subtract hours and minutes; convert between hours and minutes; solve time problems.
Prerequisite knowledge. Grade 3 time.
Materials. Counters (stones, seeds or bottle tops), paper, pencils, board or chalkboard. Low-resource options: use stones, seeds, sticks, bottle tops or drawings in the sand or on the board instead of printed materials.
Preparation. Gather the counters and draw the example pictures on the board before the lesson.
Suggested duration. 45–60 minutes. It can be split into two shorter sessions.
6–9. Teaching procedure, explanation notes, guided and independent activities
Introduction (5 min). Start with the Discover situation and let learners suggest ideas before you teach.
Explanation (10 min). Teach the Understand section with real objects first, then pictures, then symbols and words.
Guided activity (10 min). You need a clock. Learners follow the Explore steps in pairs.
Independent activity (10 min). Learners complete the independent practice and the worksheet.
Assessment and reflection (5 min). Ask each learner to say one thing they learned and how they know it.
Key questions. What is the start time? How far to the next hour?
Teacher explanation notes. Use the concrete, pictorial, abstract order: real objects first, then pictures, then symbols and words. Return to real objects whenever a learner needs support.
10–12. Differentiation, formative assessment, common misconceptions
Support. Use real objects and work with a partner; say each step aloud together. Extension. Ask learners to make up their own example and explain it to a partner.
Formative assessment. Listen to learner explanations, ask “how do you know?”, and check the independent work.
Misconceptions. Using 100 minutes in an hour. 60 minutes make an hour.
13–15. Assessment questions, answer keys, marking scheme
Use the quiz and worksheet on this page. The 12-mark exam practice scheme, the 10-mark scheme and all answers are in the answer sections above. Re-check every answer and the marking scheme before publication.
16–19. Remediation, enrichment, homework, teacher reflection
Remediation. Practise reading clocks. Enrichment. Invite learners to find or create three more examples at home or in the classroom and explain them. Homework. See above.
Teacher reflection. After teaching, record: which concepts learners understood; which misconceptions occurred; which activities worked; which learners need more practice; and what to improve next time.
Sources and standards
This lesson is based on the sources below, and no official endorsement is claimed. Reference starting points named in the Courseversity standard: Common Core State Standards for Mathematics, Cambridge Primary and the IB Primary Years Programme. Where a standard code is named, it points to the official framework.
Official standards for this topic area. Common Core State Standards for Mathematics (official site): Grade 4 » Measurement & Data. These pages list the standards that cover this topic area; read them alongside the lesson.
Research used to shape this lesson. Common Core 4.MD.A.2 and 3.MD.A.1; Cambridge Primary Mathematics Stage 4 (time intervals). These sources informed the lesson.