Last reviewed: 12 November 2026
Updated November 2026. These Grade 7 time, distance and speed notes cover the three ideas in the Grade 7 measurements sub-strand: converting units of time, converting units of distance, and working out speed in km/h and m/s. The short answer for most questions is one formula, speed = distance ÷ time, plus two conversion facts: 1 hour = 3,600 seconds and 1 kilometre = 1,000 metres. Put those together and 1 km/h is the same as 1,000 ÷ 3,600 m/s, so you divide by 3.6 to change km/h into m/s.
The questions below are original practice for Kenyan junior school learners, not an official paper. The topic list follows the Grade 7 Mathematics measurements strand in the KICD Grade Seven curriculum designs. For the rest of the year’s work, see the Grade 7 mathematics revision guide and the Grade 7 notes hub.
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Converting Units of Time
Time is measured in seconds, minutes, hours, days, weeks and years. The second is the base unit of time in the international system of units, as the NIST guide to SI units explains, and the other units are built from it.
- 1 minute = 60 seconds
- 1 hour = 60 minutes = 3,600 seconds
- 1 day = 24 hours
- 1 week = 7 days
To change a bigger unit into a smaller one, multiply. To change a smaller unit into a bigger one, divide. For example, 2 hours 15 minutes = (2 × 60) + 15 = 135 minutes, and 540 seconds = 540 ÷ 60 = 9 minutes.
Many learners lose marks when an answer such as 2.5 hours has to be written in hours and minutes. The 0.5 is half of 60 minutes, so 2.5 hours = 2 hours 30 minutes, not 2 hours 50 minutes.
Worked example: a school day
Lessons start at 8:00 a.m. and the last lesson ends at 3:40 p.m. How long is the school day in minutes? From 8:00 a.m. to 3:00 p.m. is 7 hours = 420 minutes. Add the extra 40 minutes: 460 minutes.
Converting Units of Distance
Distance is measured in millimetres, centimetres, metres and kilometres. The ones you need most often for speed are metres and kilometres.
- 1 km = 1,000 m
- 1 m = 100 cm
- To change km to m, multiply by 1,000. To change m to km, divide by 1,000.
So 3.6 km = 3,600 m, and 850 m = 0.85 km. The metric unit converter on this site, one of our free study tools, lets you check a conversion once you have done it by hand.
Working Out Speed in km/h and m/s
Speed is the distance covered in one unit of time. If a matatu covers 120 km in 2 hours, it covers 60 km in each hour, so its speed is 60 km/h. The three forms of the same relationship are:
- speed = distance ÷ time
- distance = speed × time
- time = distance ÷ speed
Always make the units match before you divide. Kilometres with hours give km/h. Metres with seconds give m/s. If a question gives metres and minutes, convert first.
Changing between km/h and m/s
Because 1 km/h = 1,000 m ÷ 3,600 s, divide a speed in km/h by 3.6 to get m/s, and multiply a speed in m/s by 3.6 to get km/h. For example, 72 km/h ÷ 3.6 = 20 m/s, and 15 m/s × 3.6 = 54 km/h.
Worked example: a runner on the track
A learner runs 400 m in 80 seconds on sports day. Speed = 400 ÷ 80 = 5 m/s. In km/h that is 5 × 3.6 = 18 km/h.
Worked example: walking to school
Amani walks 3 km to school at 4 km/h. How long does she take? Time = 3 ÷ 4 = 0.75 hours = 0.75 × 60 = 45 minutes.
Reading a speed limit sign
The design asks learners to read road signs on speed. A round sign with a red border and a number, such as 50, shows the highest speed allowed on that stretch of road in km/h. A vehicle at 15 m/s is moving at 54 km/h, so it would be above a 50 km/h limit. This is also why speed limiters on public service vehicles matter for road safety, a point the design links to this topic.
Original Practice Questions With Worked Answers
- Change 3 hours 20 minutes into minutes. 3 × 60 + 20 = 200 minutes.
- Change 7,200 seconds into hours. 7,200 ÷ 3,600 = 2 hours.
- A boda boda travels 45 km in 1 hour 30 minutes. Find its speed in km/h. 1 hour 30 minutes = 1.5 hours. 45 ÷ 1.5 = 30 km/h.
- Change 90 km/h into m/s. 90 ÷ 3.6 = 25 m/s.
- A cyclist moves at 6 m/s for 5 minutes. How far does she go, in metres? 5 minutes = 300 seconds. 6 × 300 = 1,800 m (1.8 km).
- A bus leaves Nakuru at 9:15 a.m. and covers 160 km at 64 km/h. When does it arrive? Time = 160 ÷ 64 = 2.5 hours = 2 hours 30 minutes. 9:15 a.m. + 2 h 30 min = 11:45 a.m.
Cover the answers and try each question before checking. Timed questions on this and other measurement topics are in the Grade 7 CBC Challenge. Learners who reach Grade 9 meet the topic again in the Grade 9 time, distance and speed notes. These notes are free; full revision access, including complete practice papers, is available with the KSh 20 Day Pass or the KSh 500 Monthly Pass.
Frequently Asked Questions
What is the formula for speed in Grade 7?
Speed = distance ÷ time. Rearranged, distance = speed × time and time = distance ÷ speed. Make sure the units match before you calculate.
How do you change km/h to m/s?
Divide by 3.6, because 1 km/h is 1,000 metres in 3,600 seconds. So 36 km/h = 10 m/s. To go from m/s to km/h, multiply by 3.6.
How many seconds are in one hour?
There are 3,600 seconds in one hour: 60 minutes, each of 60 seconds.
Why is 2.5 hours not 2 hours 50 minutes?
The decimal part is a fraction of an hour, not a number of minutes. 0.5 of an hour is half of 60 minutes, which is 30 minutes, so 2.5 hours = 2 hours 30 minutes.
Get the marked answers for the Grade 7 Mathematics paper, KSh 20.
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