1. How Science works:
Graphs

2. What is the best way to draw a line-graph?
Drawing a graph
What is the best way to draw a line-graph?

3. 5 steps in drawing a graph
1. Choose simple scales.
For example:
1 large square = 1 centimeter (1 cm) or
1 large square = 2 cm, or 5 cm, or 10 cm
But never choose an awkward scale,
like 1 square = 3 cm or 7 cm
Choose a scale that will make your graph
use most of the sheet of paper.

4. 5 steps in drawing a graph
1. Choose simple scales.
Put the dependent
variable
(measuring) on
the ‘y-axis’
and
the independent variable (changing) on the ‘x-axis’

5. 5 steps in drawing a graph
2. Plot the points neatly.
To mark the points we usually use an X x x
Usually you need 5 or more points for the graph. x x x x
Re-check each one before your next step.

6. 5 steps in drawing a graph
If the points form a straight line…
…draw the best straight line through them x
‘line of best fit’
Check that it looks the best straight line.

7. 5 steps in drawing a graph
4. If the points form a curve…
…draw a free-hand curve of best fit

8. 5 steps in drawing a graph
5. If a point is not on the line…
…use your apparatus to check this measurement again x
This is called an anomalous point.
You can decide to ignore anomalous points.

9. 5 steps in drawing a graph
In summary:
Choose good scales, with the dependent variable on the y-axis
Plot the points carefully
Draw a line of best fit using a ruler for a straight line graph,
or draw free-hand for a curved graph
Check anomalous points.

10. **Often referred to as the average** Ex: 2, 5, 4, 1, 2, 4, Mean = 6
For any set of data, you will need to determine the following:
Mean: This is determined by adding all the numbers in a set of data and then dividing by the number of values.
**Often referred to as the average**
Ex: 2, 5, 4, 1, 2, 4,
Mean = 6

11. For any set of data, you will need to determine the following:
Median: This is the middle number in a set of data. If the there is an even set of numbers in the data, then take the average of the two middle numbers.
Ex: 2, 3, 4, 8, 12, 16, 20
median = 8
Ex: 3, 5, 8, 11, 17, 19, 27, 30
median is = 28/2 = 14

12. Mode: This is the number that occurs most often in a set of data.
For any set of data, you will need to determine the following:
Mode: This is the number that occurs most often in a set of data.
Ex: 3, 4, 6, 6, 7, 9,9,9, 12, 12, 15
mode = 9