You will learn
- Regroup ones into tens.
- Regroup tens into hundreds.
- Add numbers in columns with regrouping.
- Check with an estimate.
Version 0.1 · published for early use · expert review pending Standards alignment: pending verification. Not yet reviewed against the Courseversity scorecard.
Student lesson
Words to know
Exchange 10 of one place for 1 of the next.
The new ten or hundred moved to the next column.
A close guess.
Digits lined up by place.
1. Discover: full baskets
A trader has 47 oranges and gets 38 more. The ones, 7 + 8, make more than 10! What do you do with the extra ten?
2. Understand: regrouping in addition
When a place adds to 10 or more, we regroup. Write the ones digit and carry the ten to the next column.
47 + 38: ones 7 + 8 = 15, write 5 and carry 1 ten. Tens 4 + 3 + 1 = 8. The sum is 85.
275 + 148: ones 5 + 8 = 13 (write 3, carry 1). Tens 7 + 4 + 1 = 12 (write 2, carry 1). Hundreds 2 + 1 + 1 = 4. The sum is 423.
3. Explore: carry the ten
You need paper and a pencil.
- Write 47 and 38 in columns.
- Add the ones: 7 + 8 = 15. Write 5, carry 1.
- Add the tens with the carried one.
- Do 275 + 148 and check with an estimate: 300 + 100 = 400.
Think about it: what did you notice?
47 + 38 = 85; 275 + 148 = 423, close to 400.
4. Practise
Guided practice
Question 1. 47 + 38?
85.
Question 2. 7 + 8 = 15. What do we write and carry?
Write 5, carry 1.
Question 3. 275 + 148?
423.
Independent practice
- 56 + 37
- 128 + 145
- 267 + 156
- 99 + 1
- 345 + 278
Answers are in the answer key below. Try first, then check.
5. Apply: everyday mathematics
A school has 275 girls and 148 boys. How many pupils?
Show a sample answer
423 pupils.
6. Common mistake
Fix: Write the carry above the next column and add it.
7. Check and master
Answer all questions. You will see feedback after each one.
Your result appears here after you answer every question.
8. Key takeaways
- Regroup when a column makes 10 or more.
- Carry to the next place.
- Estimate to check.
9. Next lesson
Next lesson: Subtraction within 100. Keep going with the next idea in this course.
Printable worksheet
- 56 + 37
- 128 + 145
- 267 + 156
- 99 + 1
- 345 + 278
Homework
Add the price of two items with ones that make more than 10, such as 28 and 35.
Answer key and marking scheme
| Question | Expected response | Marks |
|---|---|---|
| 56 + 37 | 93 | 2 |
| 128 + 145 | 273 | 2 |
| 267 + 156 | 423 | 2 |
| 99 + 1 | 100 | 2 |
| 345 + 278 | 623 | 2 |
| Total | 10 |
Practice answers: Worksheet: 1 93; 2 273; 3 423; 4 100; 5 623.
Quiz answers: 1 A, 2 B, 3 C, 4 A, 5 B, challenge C.
Mastery and remediation
| Objective | Bronze (Developing) | Silver (Proficient) | Gold (Advanced) |
|---|---|---|---|
| O1 Regroup ones into tens | 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 Regroup tens into hundreds | 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 Add numbers in columns with regrouping | 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 Check with an estimate | 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 |
Proposed Courseversity thresholds for this page: Bronze = at least 3 of 5 core questions correct; Silver = all 5; Gold = all 5 plus the challenge. A badge is never a full record of progress.
If a learner struggles
- Find the misconception: Forgetting to add the carried ten. Write the carry above the next column and add it.
- Explain another way: use real objects first, then pictures.
- Show a simpler example: Use a ten frame to exchange 10 ones for 1 ten.
- 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.
Teacher package
1–5. Objectives, prerequisites, materials, preparation, duration
Lesson objectives. Learners will: regroup ones into tens; regroup tens into hundreds; add numbers in columns with regrouping; check with an estimate.
Prerequisite knowledge. Lessons 2 and 3.
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. 35–45 minutes.
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 paper and a pencil. 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.
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. Forgetting to add the carried ten. Write the carry above the next column and add it.
13–15. Assessment questions, answer keys, marking scheme
Use the quiz and worksheet on this page. The 10-mark scheme and all answers are in the answer key above. Re-check every answer and the marking scheme before publication.
16–19. Remediation, enrichment, homework, teacher reflection
Remediation. Use a ten frame to exchange 10 ones for 1 ten. 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
Alignment is pending verification and no external 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. Specific standard codes will be added once checked against the official documents.