• I can plot coordinates.• Given the equation of a straight line, I can complete a table

of values.• From a table of values, I can draw a straight line.• Given a set of data, I can plot points on a scatter graph.• I can draw a line of best fit.

S3 BLOCK 8 Straight Line

Coordinates

I can plot coordinates.

Review: Coordinates

Remember that the first number is the -coordinate and the second number is the -coordinate.

Along first, then up or down.

Example 1

(a) Plot the points (1, 2) (2,3) (3,4) (4,5) and (5,6).(b) Draw a straight line through these points.

Plot the points (1, 2) (2,3) (3,4) (4,5) (5,6)

Table of values

Given the equation of a straight line, I can complete a table of values.

From a table of values, I can draw a straight line.

Table of values

Complete the table below for

To do this, replace different values of into the equation

-2 -1 0 1 2

Replace then then then then then

-2 -1 0 1 2-1-3 1 3 5

Plot the points (-2, -3) (-1, -1) (0, 1) (1, 3) (2, 5)

A straight line can be drawn through these points

-2 -1 0 1 2-1-3 1 3 5

Scatter graph

Given a set of data, I can plot points on a scatter graph.

I can draw a line of best fit.

Scatter graphs

Scatter graphs are used to represent and compare two sets of data.By looking at a scatter diagram it is possible to say whether there is any connection (correlation) between the two sets of data.

Line of Best Fit

When there is a correlation between sets of data on a scatter graph, it is possible to draw a line of best fit.

When drawing a line of best fit the aim is to keep the distance of all the points from the line to a minimum.

Sometimes it is helpful to try to keep the number of points above the line as the same as the number of points below the line.

ExampleIn a class 10 pupils tool a Science test and an Maths test.Their scores are listed in the table.

(a) Illustrate this data with a scatter graph.(b) Draw a best fitting line on the graph

Pupil A B C D E F G H I JMaths Score 2 10 15 4 9 6 14 19 12 18Science Score 6 12 18 3 11 8 14 17 10 20

Scie

nce

Scor

e

Maths Score0 5 10 2015

0

5

10

15

20H

B

C

D

E

F

G

A

I

J

Scie

nce

Scor

e

Maths Score0 5 10 2015

0

5

10

15

20H

B

C

D

E

F

G

A

I

J