# Graph protocols

## Graph protocols

Most graphs have two axes – an x-axis (horizontal and represents the independent variable) and a y-axis (vertical and represents the dependent variable). Sometimes you may use several data sets on the one graph. If you are investigating the impact of fertiliser on plant growth, the x-axis may not represent fertiliser/non-fertiliser but time over which the data was recorded. Two sets of points (often with a key or in different colours) are plotted to help demonstrate the impact of the fertiliser. It may show that initially the fertilised plants grew faster, but that the impact gradually reduced.

A common mistake when constructing graphs is for students to place the data points along the axes at equal distances rather than to scale. For instance, data recorded at 1 minute, 5 minutes and 15 minutes would be equally spaced along the x-axis. The resultant line between the plotted points will therefore not truly represent the relationship.

TaLe Student Research Project has a section on graphing and tables (collecting data).

Learn more about the processes of tabulating and graphing data from this University of Tasmania web site.

This web site has a tutorial on the use of Excel for graphing.

If you want to learn more about numeracy teaching and learning the National Literacy and Numeracy Week web site has a wide range of resources such as ‘Critical Numeracy in context’ a seven minute video by Dr Jane Watson from the University of Tasmania.