Today we compare. Which is longer? Which is shorter? Which is heavier? Which is lighter?
Pencils come in different lengths. Line them up to compare. Photo: MichaelMaggs, CC BY-SA 3.0, via Wikimedia Commons.
Longer and shorter
To compare two things, line them up at one end. Then look at the other end.
✏️✏️✏️✏️✏️ 🖍️🖍️🖍️
The pencil goes further. The pencil is longer. The crayon is shorter.
If they end at the same place, they are the same length.
Tall and short
People and trees can be tall or short. Stand back to back with someone on flat ground. Who is taller?
Heavy and light
Hold one thing in each hand. The one that pulls your hand down more is heavier. The other is lighter.
A watermelon is heavier than an apple. A feather is very light.
A watermelon is much heavier than an apple. Hold an apple: is it light or heavy? Photo: Peculiar grace, CC0, via Wikimedia Commons.
Big is not always heavy
A big balloon is light. A small stone can be heavy. We must feel or use a balance to check, not just look.
On a balance or a see-saw, the heavier side goes down.
A feather is very light. You can hardly feel it in your hand. Photo: Joao Estevao Andrade de Freitas, Public domain, via Wikimedia Commons.
Try it
TRY ITCompare it
Pick a game. Then tap your answer.
Let’s practise
Point, say or draw. Open each answer after trying.
1. Find a spoon and a fork. Line them up at one end. Which is longer?
Show answer
Answers will vary. Check that the ends were lined up first.
2. Stand back to back with an adult. Who is taller?
Show answer
Usually the adult. Say: the adult is taller, I am shorter.
3. Hold a shoe in one hand and a sock in the other. Which is heavier?
Show answer
Usually the shoe is heavier.
4. Which can be small but heavy? (a) a balloon (b) a stone (c) a feather
Show answer
(b) a stone.
Quick check
Try these three on your own first. An adult may read the words.
1. Two strips start at the same line. The red strip goes further. Which is longer?
The red strip
The other strip
They are the same
Show answer
The red strip. The one that reaches further from the same start is longer.
2. Which is heavier?
A feather
A watermelon
A leaf
Show answer
A watermelon. A watermelon is heavy. Feathers and leaves are light.
3. Before we compare two lengths, what do we do?
Line them up at one end
Pick the brighter one
Close our eyes
Show answer
Line them up at one end. Line up one end, then look at the other end.
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Maths lesson 14: Long and Short, Heavy and Light — worksheet
Point, draw or tell an adult. An adult can write for you.
Draw a long snake and a short snake. Circle the longer one.
Draw something heavy and something light. Write or say heavy and light.
Draw a see-saw with a heavy thing on one side. Which side goes down?
Say these words with an adult. Can you use each one in a sentence?
long · longer · short · shorter · tall · heavy · heavier · light · lighter · compare · balance
Try it at home
Line up three shoes from one end. Find the longest and the shortest.
Heft two things from the kitchen, like a tin and a packet of crackers. Guess first, then feel.
Make a simple balance with a coat hanger and two bags. Which bag goes down?
For parents and teachers
After this lesson, your child should be able to:
line up two objects from one end and say which is longer, shorter or the same length
hold two objects and say which is heavier or lighter
give one example where a smaller object is heavier than a bigger one
Use safe, real objects for hefting, not only pictures. Comparing directly comes before measuring with units such as centimetres or kilograms.
Accept pointing, speaking, signing or communication aids. An adult can scribe. Observe the hands-on work as well as the Quick check; the badge records supported completion only.
Choose centimetres, metres or kilometres for a length.
Convert between centimetres and metres, and between metres and kilometres.
Read a centimetre ruler, round a length to the nearest metre or kilometre, and solve length problems.
A pencil, the classroom and the road to another town are all lengths, but we do not measure them with the same unit. A pencil is a few centimetres. A classroom is a few metres. A drive from San Fernando to Port of Spain is measured in kilometres. In this lesson you will choose the unit, change from one unit to another, read a ruler and round a length.
These rulers are marked in centimetres. Some also show inches. For this lesson, use the centimetre scale. Photo: Estabiano, CC0, via Wikimedia Commons.
Choosing the unit
Use centimetres (cm) for short objects: a crayon, a copybook, your handspan. Use metres (m) for bigger lengths you could pace: the classroom, a door, a cricket pitch. A cricket pitch is about 20 m. Use kilometres (km) for long distances: the road between two towns.
Length
Best unit
a new pencil
cm
the classroom
m
San Fernando to Port of Spain
km
After you estimate, check that the size makes sense. A pencil is about 15 cm, not 15 m. 15 m is longer than a classroom. A classroom might be about 8 m, not 8 km.
Worked example 1
Which unit is best for the length of the classroom: cm, m or km?
Show me how
The classroom is much longer than a pencil, so centimetres would be a big number.
It is much shorter than the road to another town, so kilometres are too big.
Metres are best.
Changing units
The units are connected by hundreds and thousands.
This
is the same as
1 m
100 cm
1 km
1 000 m
To change metres into centimetres, multiply by 100. To change kilometres into metres, multiply by 1 000. To go back, divide.
3 m = 3 × 100 cm = 300 cm. 250 cm = 2 m 50 cm, because 200 cm is 2 m and 50 cm are left. 2 km = 2 000 m. 1 500 m = 1 km 500 m.
Worked example 2
A rope is 4 m long. How many centimetres is that? A path is 3 km long. How many metres is that?
Show me how
1 m = 100 cm, so 4 m = 4 × 100 = 400 cm.
1 km = 1 000 m, so 3 km = 3 × 1 000 = 3 000 m.
The rope is 400 cm. The path is 3 000 m.
Watch out! A common mistake
Do not mix up the two rules. 1 m is 100 cm, not 1 000 cm. 1 km is 1 000 m, not 100 m. Say the pair out loud: metre and hundred, kilometre and thousand.
Reading a ruler
Line up one end of the object with the 0 mark if you can. Read the mark at the other end. That number is the length in centimetres.
The bar starts at 0 and ends at 7. It is 7 cm long.
Sometimes the object does not start at 0. Then the length is end minus start.
The bar starts at 2 and ends at 9. It is 7 cm long.
Worked example 3
A crayon starts at the 3 cm mark and ends at the 11 cm mark. How long is the crayon?
Show me how
The crayon does not start at 0, so do not say 11 cm.
Length = end minus start = 11 − 3.
The crayon is 8 cm long.
Rounding and length problems
To round to the nearest metre, look at the centimetres. 50 cm or more rounds up to the next metre. Less than 50 cm rounds down.
6 m 20 cm is nearer 6 m. 6 m 80 cm is nearer 7 m. 6 m 50 cm rounds up to 7 m.
To round to the nearest kilometre, look at the metres. 500 m or more rounds up. 4 km 200 m rounds to 4 km. 4 km 500 m rounds to 5 km.
Worked example 4
A roll of ribbon is 2 m 70 cm, rounded to the nearest 10 cm already. Round the length to the nearest metre. Then three friends each need 40 cm of ribbon. How many centimetres is that altogether?
Show me how
70 cm is more than 50 cm, so 2 m 70 cm rounds up to 3 m.
Three pieces: 3 × 40 cm = 120 cm.
To the nearest metre the roll is 3 m. The three pieces are 120 cm, which is 1 m 20 cm.
Try it
TRY ITLength lab
Choose a unit, convert, read a ruler, round a length and solve a length problem.
Let’s practise
Work out each one in your copybook. Open Hint if you are stuck, then open Show answer to check your working.
To print this worksheet, tap the button. To save it as a PDF instead, look in the print window for an option like Save as PDF, Save to PDF, Print to PDF or Download. The name is a little different on each phone, tablet and computer.
1. Which unit is best for the width of a copybook: cm, m or km?
Hint
A copybook is a small object.
Show answer
cm
2. Which unit is best for the distance from San Fernando to Port of Spain?
Hint
It is a long drive, not a length you pace across the room.
Show answer
km
3. How many centimetres are in 6 m?
Hint
1 m = 100 cm.
Show answer
600 cm
4. How many metres are in 2 km?
Hint
1 km = 1 000 m.
Show answer
2 000 m
5. Write 350 cm in metres and centimetres.
Hint
100 cm = 1 m. How many hundreds are in 350?
Show answer
3 m 50 cm
6. A pencil starts at 1 cm and ends at 16 cm on a ruler. How long is it?
Hint
End minus start.
Show answer
15 cm
7. Round 8 m 40 cm to the nearest metre.
Hint
Is 40 cm enough to round up?
Show answer
8 m
8. Ribbon costs 2 dollars for 50 cm. How much do 150 cm cost?
Hint
How many lots of 50 cm are in 150 cm?
Show answer
6 dollars
Quiz
Lesson quiz: 10 questions
Answer every question, then press Check my answers. Score 8 or more to earn the Length Leader badge.
Length: worksheet
Name: ____________________ Date: ______________
Part A: Let’s practise
1. Which unit is best for the width of a copybook: cm, m or km?
2. Which unit is best for the distance from San Fernando to Port of Spain?
3. How many centimetres are in 6 m?
4. How many metres are in 2 km?
5. Write 350 cm in metres and centimetres.
6. A pencil starts at 1 cm and ends at 16 cm on a ruler. How long is it?
7. Round 8 m 40 cm to the nearest metre.
8. Ribbon costs 2 dollars for 50 cm. How much do 150 cm cost?
Part B: Quiz
1. The best unit for the length of a classroom is
(a) cm
(b) m
(c) km
(d) g
2. How many centimetres are in 4 metres?
3. How many metres are in 3 kilometres?
4. 250 cm is the same as
(a) 25 m
(b) 2 m
(c) 250 m
(d) 2 m 50 cm
5. 1 kilometre = 100 metres.
True or False? Circle one: True / False
6. A pencil is about 15 cm long. Someone records it as 1 m 50 cm. Is that reasonable?
(a) No. 1 m 50 cm is about the height of a child.
(b) Yes. 15 cm is about 1 m 50 cm.
(c) No. A pencil is about 15 km.
(d) Yes. It is close enough.
7. A ribbon starts at 2 cm and ends at 9 cm on a ruler. How many centimetres long is it?
8. 6 km 700 m to the nearest kilometre is
(a) 6 km
(b) 670 m
(c) 7 km
(d) 8 km
9. 50 cm or more rounds up to the next metre.
True or False? Circle one: True / False
10. Three pieces of ribbon are each 40 cm long. How many centimetres is that altogether?
Answers (for the adult)
Part A
1. cm
2. km
3. 600 cm
4. 2 000 m
5. 3 m 50 cm
6. 15 cm
7. 8 m
8. 6 dollars
Part B
1. (b) m
2. 400
3. 3000
4. (d) 2 m 50 cm
5. False
6. (a) No. 1 m 50 cm is about the height of a child.
7. 7
8. (c) 7 km
9. True
10. 120
Recap
Use cm for short objects, m for room-sized lengths and km for distances between towns.
1 m = 100 cm. 1 km = 1 000 m.
If an object does not start at 0, its length is end minus start.
50 cm or more rounds up to the next metre. 500 m or more rounds up to the next kilometre.
Check that an answer is a sensible size for the object.
Words to know
centimetre (cm)
A small unit of length. 100 cm make 1 m. Example: A crayon is about 8 cm long.
metre (m)
A unit of length for rooms, doors and pitches. 1 m = 100 cm. Example: The classroom is about 8 m long.
kilometre (km)
A unit of length for long distances. 1 km = 1 000 m. Example: The drive is measured in kilometres.
estimate
A sensible guess of a measure, close but not exact. Example: I estimate the table is 2 m long.
round
To give a measure to the nearest unit you were asked for. Example: 6 m 80 cm rounds to 7 m.
Try it at home
Estimate the length of the kitchen table in metres. Then measure it with a tape if you have one, and see how close you were.
Use a ruler to measure a pencil, a spoon and a copybook in centimetres. Write start, end and length for each one.
Test tips
Tips for class tests
Write the unit in your answer. 400 without a unit could be cm or m.
On a ruler, subtract the start from the end when the object does not begin at 0.
Before you leave a word problem, ask: is this a sensible length for that object?
For parents and teachers
After this lesson, your child should be able to:
choose centimetres, metres or kilometres and explain why;
convert between metres and centimetres, and between kilometres and metres;
read a centimetre scale, round a length to the nearest metre or kilometre, and solve length problems, including a check that the estimate was reasonable.
The halfway rule used here matches the rounding they already use with whole numbers: 50 cm rounds up to the next metre, and 500 m rounds up to the next kilometre. A 30 cm ruler at home is enough for the measuring task.
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Which is longer? Which is heavier? Today we measure and compare things.
Longer and shorter
To compare lengths, line things up at the same starting line. Then look at the other end.
✏️ pencil: ▬▬▬▬▬ 🖍️ crayon: ▬▬▬
The pencil is longer. The crayon is shorter. With three things we can say longest and shortest.
Measuring with paper clips
We can measure with paper clips, hand-spans, blocks or footsteps. Put them end to end:
in a straight line
no gaps
no overlaps
then count them
A book is 7 paper clips long. A pencil is 5 paper clips long. The book is 2 clips longer.
Heavier and lighter
A balance shows which side is heavier. The heavier side goes down. Photo: Nikodem Nijaki, CC BY-SA 3.0, via Wikimedia Commons.
Big things are not always heavier! A big balloon is very light. A small stone can be heavy.
TRY ITMeasure it!
Choose a game. Then tap your answer.
Let’s practise
Try each one. Then tap Show answer to check.
1. A ribbon is 6 clips long. A string is 9 clips long. Which is longer?
Show answer
The string.
2. Why must we leave no gaps between the clips?
Show answer
Gaps would make us count too few clips, so the answer would be wrong.
3. A table is 8 hand-spans long. A chair is 4 hand-spans long. How many more spans is the table?
Show answer
4 more hand-spans.
4. Which is heavier: a coconut or a feather?
Show answer
A coconut.
5. On a balance, the left side goes down. Which side is heavier?
Show answer
The left side.
6. Which is lighter: a big pillow or a small brick?
Show answer
The big pillow.
Quick check
1. Put in order, shortest first: a bus, a pencil, a car.
Show answer
Pencil, car, bus.
2. Is a bigger thing always heavier?
Show answer
No. A balloon is big but light.
3. What do we call it when both sides of a balance are level?
Show answer
They are as heavy as each other (they balance).
Maths words
Say these words with a grown-up. Can you use each one in a sentence?
long · longer · longest · short · shorter · shortest · tall · tallest · as long as · hand-span · heavy · heavier · light · lighter · as heavy as · weigh · balance
Try it at home
Measure your bed with hand-spans. Measure the table. Which is longer?
Line up your shoes and your family’s shoes from shortest to longest.
Hold a mango in one hand and a lime in the other. Which feels heavier? Check with a coat-hanger balance.
Make a pattern with long and short straws: long, short, long, short …
For parents and teachers
After this lesson, your child should be able to:
compare and order three or more objects by length (longest/shortest)
measure length using paper clips, hand-spans or blocks laid end to end with no gaps and no overlaps
compare masses using a balance and read pictures of balances
explain that a big object is not always heavier
Rice or beans in two identical cups hanging from a coat hanger makes a good home-made balance.
