Introduction to directed numbers

Lesson

Practice

Lesson

The OPPOSITE direction

When we change direction, and move the opposite way, we can compare it to moving along a number line. Many things in life involve going in the opposite direction, such as the bus we see in our first video. Our number line shows us how the direction can be seen as positive or negative.

As well as left and right, we might think of moving from east to west, as this question does. Can you think of any other pairs of words that mean the opposite direction?

Worked example

Question 1

A man drove $10$10 km $East$ , then $24$24 km $West$ , then $8$8 km $East$ .

Is he now East or West of his original position?
Back to his original position
A
$West$
B
$East$
C
How far $West$ is he from his original position?

There are many ways we can see examples of positive and negative numbers, so we'll take a look at some others in this video.

Up and down

There are many other ways that positive and negative numbers are useful, such as :

receiving money or owing money
the temperature rising or decreasing
going up or down in a lift

In these cases we can use positive and negative numbers to show these opposite relationships. Let's see how a lift changes directions, thinking about numbers.

Worked Examples

Question 2

$Victoria$ enters an elevator on the ground floor (level $0$0). She goes $up$ $5$5 floors, then $down$ $8$8 floors then $up$ $3$3 floors.

Does $Victoria$ end up above or below ground level, or back where she started?
above
A
below
B
back at ground level
C

Question 3

The temperature over a day rose and fell. It ended up $0$0 degrees Fahrenheit from where it started at the beginning of the day.

What can we conclude about the temperature?

The temperature is higher than it was at the beginning of the day.
A
The temperature is lower than it was at the beginning of the day.
B
The temperature is exactly the same as it was before.
C

Outcomes

5.G.SSU.1

Gets the feel of perspective while drawing a 3-D object in 2-D. (Added: scales in maps)