Primary 5 Maths: Four Operations with Decimals — Tutor Lesson Plan (alignment, places, division)

2026-10-27

Tutor lesson-prep guides · Primary maths

Addition and subtraction depend on alignment; multiplication and division depend on counting places. Split the four operations into two groups and students stop mixing the methods.

Objectives — the student can align decimal points, multiply as whole numbers then place the point, divide by a decimal by scaling both numbers, and estimate to check the size of the answer.

01 Prerequisites (3-minute check)

If any of these fails, fix it before the lesson starts.

Skill	Quick check	Pass mark
Place value	In 3.45, what is the 4 worth?	Four tenths
Whole-number multiplication	36 × 25	900
Whole-number division	72 ÷ 9	8

02 Lesson flow (45 minutes)

Time	Stage	Tutor does	Student does
0-5 min	Estimate	Ask: roughly how much is 12.5 − 4.75?	Estimate about 7 to 8
5-14 min	Alignment	Show 12.5 − 4.75 with a zero filled in	Write 12.50 − 4.75
14-24 min	Places	3.6 × 2.5 via 36 × 25 = 900	Do one alone
24-34 min	Decimal divisor	0.6 ÷ 0.25 becomes 60 ÷ 25	Do 7.2 ÷ 0.9
34-42 min	Mixed and check	One mixed question, checked by estimating	Say whether the answer is reasonable
42-45 min	Exit check	Three questions marked at once	Finish alone

03 Teaching script (read it out)

Scene 1: Align the points

12.5 − 4.75: put the decimal points in one line and write 12.50.
Fill the missing place with a zero so nothing is borrowed from the wrong column.

Student writes 12.50 − 4.75 = 7.75 and circles the points.

Scene 2: Multiply as whole numbers first

3.6 × 2.5: first 36 × 25 = 900.
The factors have one and one decimal place, so the product takes two: 9.00, written 9.

Student counts the total number of decimal places before writing the point.

Scene 3: Scale both numbers to divide

0.6 ÷ 0.25: the divisor has two decimal places, multiply both by 100: 60 ÷ 25 = 2.4.
Both numbers move, never just the divisor.

Warn: for a one-place divisor such as 0.9, multiply both by 10 only.

04 Question types and worked steps

Type	Example	Steps	Answer
Subtraction	12.5 − 4.75	Align with a zero	7.75
Multiplication	3.6 × 2.5	36 × 25 = 900, two places	9
Division by a decimal	0.6 ÷ 0.25	60 ÷ 25	2.4
Division	4.8 ÷ 1.2	48 ÷ 12	4

Sanity check (teach this): Multiplying by a number below 1 makes the answer smaller (3.6 × 0.5 = 1.8); dividing by one makes it larger (0.6 ÷ 0.25 = 2.4).

05 Independent practice (3 questions)

Question	Answer	What to watch
9.05 + 3.8	12.85	Points aligned
2.4 × 0.5	1.2	Places counted
7.2 ÷ 0.9	8	Both numbers scaled by 10

06 Common mistakes and what to say

Mistake	Student writes	Say this
Points not aligned	12.5 − 4.75 = 12.03	Put the points in one line and fill with zeros.
Wrong number of places	3.6 × 2.5 = 90	Two decimal places in total.
Only the divisor scaled	0.6 ÷ 0.25 becomes 0.6 ÷ 25	Both numbers must be multiplied.
Trailing zeros kept	answers 9.00 or 2.40	Drop the trailing zeros: 9 and 2.4.

07 Homework (paper, section and question numbers)

Primary 5 first-term paper — Section B, questions 1 to 8
Primary 5 second-term paper — Section B, questions 1 to 6

08 Exit check (last 5 minutes)

Question	Answer	Decision
6.75 + 3.25	10	All right: move to percentages
1.5 × 1.6	2.4	One wrong: re-teach place counting
0.36 ÷ 0.4	0.9	Two wrong: repeat scene 3

09 Tutor FAQ

Is “move the decimal point” acceptable?

Yes, but say “multiply both numbers by the same power of ten”, otherwise students move only one.

Can they use a calculator?

Not in this lesson. Place counting and alignment are the point; calculators are for checking.

Do they need L to cm³ conversions here?

No, that belongs to the volume lesson.

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