When we compare the length of something, we can see which number is smallest, or largest. A number line is a great way to do this. Length is a unit of measurement that we can use to measure how tall something is, how wide it is, how long it stretches, etc.

Watch how we compare length to decide which tablet to buy for our homework.

Worked Examples

Question 1

A ladybeetle is $4$4 mm long and a bull ant is $7$7 mm long.

Mark these two lengths on the number line.
Which insect is $longer$ ?
$Ladybeetle$
A
$Bull Ant$
B

QUESTION 2

The heights of three men were measured.

Which list shows these men's heights from tallest to shortest?
Man 2, Man 3, Man 1
A
Man 3, Man 1, Man 2
B
Man 2, Man 1, Man 3
C
Man 3, Man 2, Man 1
D
Man 1, Man 2, Man 3
E
Man 1, Man 3, Man 2
F

How can I order these?

This time, I'm going to have to look at the size of my objects (well, they're people this time!) to see how to put things in order. I wrote down their names, but forgot to label their height. I have $3$3 people, and $3$3 lengths to put together. Watch video 2 to see I can fix this.

Worked example

Question 3

The heights of three men were measured.

Which list shows these men's heights from tallest to shortest?
Man 2, Man 3, Man 1
A
Man 3, Man 1, Man 2
B
Man 2, Man 1, Man 3
C
Man 3, Man 2, Man 1
D
Man 1, Man 2, Man 3
E
Man 1, Man 3, Man 2
F

Remember!

If our objects have the same unit of measurement, we are able to compare the numbers, to put them in order.

Order objects by length

Comparing length