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Primary 1 Maths | Addition within 20 Lesson-Prep Guide (for tutors) | Make-ten, number line, commutativity
A pupil can get 8 + 5 = 13 by counting fingers, but that method fails in Primary 2. This lesson replaces counting with splitting: 8 needs 2 to reach 10, so take 2 out of the 5.
01 Prerequisites (3-minute check)
If any of these fails, fix it before the lesson starts.
| Skill | Quick check | Pass mark |
|---|---|---|
| Number bonds to 10 | knows which pairs make 10 | 1+9 up to 5+5 |
| Number line | can count forward on a line | from 8 to 13 |
02 Lesson flow (40 minutes)
| Time | Stage | Tutor does | Student does |
|---|---|---|---|
| 0–5 min | Diagnose | ask how many 8 needs to reach 10 | answers 2 |
| 5–15 min | Make-ten | 8 + 5: split 5 into 2 + 3 | writes 8 + 2 + 3 = 13 |
| 15–25 min | Number line | start at 8, jump 5 | lands on 13 |
| 25–33 min | Commutativity | 3 + 5 against 5 + 3 | same answer, with a reason |
| 33–40 min | Exit check | three questions | no fingers |
03 Teaching script (read it out)
Scene 1: Act 1: Make-ten by splitting the second number
Tutor line: “How many does 8 need to reach 10? Take 2 from the 5. How many are left in the 5?”
Scene 2: Act 2: Start from the larger number on the line
Tutor line: “Put your finger on 8. Jump 5 forward. One, two, three, four, five. Where are you?”
Scene 3: Act 3: Commutativity is seen, not memorised
Tutor line: “You swapped them. Did the total change? So what about 3 + 5 and 5 + 3?”
04 Question types and worked steps
| Type | Example | Steps | Answer |
|---|---|---|---|
| Carrying addition: 8 + 5 | find what the second number needs to reach ten, split, add ten, add the rest | past ten you just write the digit | |
| Number line: from 8 jump 5 | set the start, jump forward, read the landing point | start from the larger number | |
| Commutativity: 3 + 5 = ? + 3 | identify the known addend, use the rule to fill the blank | the two addends swap | |
| Word problem: Ben has 9 sweets and buys 7 more | find both numbers, make ten, give the unit | the answer needs “sweets” |
05 Independent practice (3 questions)
| Question | Answer | What to watch |
|---|---|---|
| 8 + 5 = ? | 13 | 8 + 2 + 3 |
| 9 + 7 = ? | 16 | 9 + 1 + 6 |
| 7 + 4 = ? | 11 | 7 + 3 + 1 |
| On a number line, jump 8 forward from 6 | 14 | or jump 6 from 8 |
| 4 + 9 = 9 + ? | 4 | commutativity |
06 Common mistakes and what to say
| Mistake | Student writes | Say this |
|---|---|---|
| Counting from one on fingers | counting 8 + 5 from 1 | “Do not start at 1. 8 needs 2 to reach 10, so take 2 from the 5.” |
| Splitting the wrong addend | splitting 8 into 5 + 3 | “Split the second number, not the first.” |
| Jumping from the first number | 3 + 9: jumping 9 from 3 | “Start at 9 and jump 3.” |
| Missing the unit | answering 13 with no unit | “Thirteen what? Say thirteen sweets.” |
07 Homework (paper, section and question numbers)
- Addition within 20 practice (in-school) — questions 1–8: make-ten
- Primary 1 maths paper 2 — questions 1–5: addition word problems
08 Exit check (last 5 minutes)
| Question | Answer | Decision |
|---|---|---|
| 7 + 6 = ? | 13 | if wrong: reteach splitting 6 into 3 + 3 |
| 9 + 8 = ? | 17 | if wrong: reteach that 9 needs 1 |
| 5 + 7 = 7 + ? | 5 | if wrong: reteach commutativity |
09 Tutor FAQ
The pupil gets the right answer with fingers. Why stop it?
Fingers work up to 20 and then fail completely at fractions and three-digit numbers in Primary 2. Make-ten extends; replacing it later is harder than building it now.
Must the second addend always be the one split?
Yes. Fixing one step gives the pupil a single stable procedure. Allowing either split creates confusion about which number to break.
Should number bonds to 10 be memorised?
Yes, to the point of instant recall. The five pairs from 1+9 to 5+5 are the prerequisite for make-ten.
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A TutorZone lesson-prep guide. Written by the TutorZone team; questions and lesson flow are original and are not taken from any school or publisher material.