Primary 6 Maths: Speed — Tutor Lesson Plan (formula triangle, unit conversion)

2026-10-27

Tutor lesson-prep guides · Primary maths

Nine out of ten speed errors are unit errors: minutes left as minutes, kilometres mixed with metres. This lesson makes the unit check a compulsory step.

Objectives — the student can state speed = distance ÷ time, rearrange it for distance and time, convert km/h to m/s by dividing by 3.6, and unify units before calculating.

01 Prerequisites (3-minute check)

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

Skill	Quick check	Pass mark
Division	240 ÷ 4	60
Time conversion	45 minutes in hours	0.75 hours
Decimal multiplication	60 × 2.5	150

02 Lesson flow (50 minutes)

Time	Stage	Tutor does	Student does
0-6 min	Context	120 km in 2 hours: how far in one hour?	Answer 60 km
6-16 min	Triangle	Write the triangle and derive three formulas	Find distance and time
16-26 min	Units	45 minutes becomes 0.75 hours	One alone
26-36 min	km/h to m/s	36 km/h becomes 10 m/s	Convert 72 km/h
36-44 min	Two-part journey	Find the average speed of two legs	One alone
44-50 min	Exit check	Three questions marked at once	Finish alone

03 Teaching script (read it out)

Scene 1: Speed is “how far in one hour”

120 km in 2 hours is 60 km each hour, written 60 km/h.
So speed = distance ÷ time, and the unit is built from both.

Student says “distance divided by time, unit included”.

Scene 2: The triangle gives the rearrangement

Put D on top, S and T below.
Distance is S × T, time is D ÷ S, speed is D ÷ T. Draw it once instead of memorising three formulas.

Student draws the triangle and states all three.

Scene 3: Unify units or fail

45 minutes must become 0.75 hours before entering a km/h formula.
For km/h to m/s divide by 3.6: 36 ÷ 3.6 = 10 m/s; multiply to go back.

Rule: write the unit line before touching the numbers.

04 Question types and worked steps

Type	Example	Steps	Answer
Find speed	120 km, 2 hours	120 ÷ 2	60 km/h
Find distance	60 km/h, 2.5 hours	60 × 2.5	150 km
Find time	90 km at 45 km/h	90 ÷ 45	2 hours
Convert	36 km/h	36 ÷ 3.6	10 m/s

Sanity check (teach this): At a steady speed, doubling the time doubles the distance; an answer where longer time gives less distance means the operation was inverted.

05 Independent practice (3 questions)

Question	Answer	What to watch
150 km in 3 hours	50 km/h	Distance over time
40 km/h for 2.5 hours	100 km	Multiplying
72 km/h in m/s	20 m/s	Dividing by 3.6

06 Common mistakes and what to say

Mistake	Student writes	Say this
Multiplying instead of dividing	120 × 2 = 240 km/h	Speed is distance divided by time.
Minutes used as hours	45 minutes entered as 45	Convert to 0.75 hours first.
Conversion the wrong way	36 km/h becomes 129.6 m/s	Divide by 3.6 to get m/s.
No unit	answers 60	60 what? Write km/h.

07 Homework (paper, section and question numbers)

Primary 6 first-term paper — Section E, questions 7 to 9
Primary 6 second-term paper — Section D, questions 4 to 6

08 Exit check (last 5 minutes)

Question	Answer	Decision
150 km in 3 hours	50 km/h	All right: Primary 6 main line complete
40 km/h for 2.5 hours	100 km	One wrong: re-teach the triangle
72 km/h in m/s	20 m/s	Two wrong: repeat the unit step

09 Tutor FAQ

Should they memorise 3.6?

Yes, but explain it: 1000 m over 3600 s is 1 over 3.6.

Average speed of two legs?

Total distance over total time, never the average of the two speeds.

How hard should word problems get?

One-way or two legs in the same direction; meeting problems belong to Secondary 1.

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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.