Scientific Skills: Graphing in the HSC

8 Mins Read | Written by Sara Lowe

Key Points Summary

Graphs are visual diagrams which map the relationship between different variables
There are many different types of graphs (e.g., column, line, pie) used to show different types of information
There are key features of a graph that you must include if asked to draw a graph in the HSC

Content

Syllabus

Students:

Extracting and reorganising secondary-sourced information in the form of flow charts, tables, graphs, diagrams, prose, keys, spreadsheets and databases
- Construction and analysis of graphs

What are Graphs?

Graphs are visual diagrams which map the relationship between different variables. They allow us to make conclusions about relationships and the effects of changing one variable on another.

What are the Different Types of Graphs and What Do we use them For?

There are many different types of graphs which you may be familiar with, such as column, pie, line and bar graphs, just to name a few. These different types of graphs exist to present different information in a manner which is most appropriate to understanding the relationships between variables.

In the HSC, NESA may test your understanding of different graph types – what are they and what are they used for.

Sample NESA HSC Graphing Question

The following question has been taken from the 2019 Biology Exam Paper and is an example of how NESA may test your graphing skills:

Answer: B

The answer is B – a column graph. This is because we are interested in the number of species found in different categories (i.e. environments). The graph must hence show 2 bits of information:

1. The different habitats (i.e. rainforest, salty marsh, dry plains etc.)

2. The number of species in each of these habitats

Option B has both of these bits of information.

A can be eliminated as we are not interested in the proportion of species found in each habitat but rather the number of each species found in each habitat. The title of graph A also mentions ‘number of animals’ when we are interested in ‘number of species’.

C can be eliminated as it it’s a line graph. A line graph is inappropriate in this scenario as we are not interested in a trend which can be observed overtime. Rather we just want to know how many species are living in each habitat.

D can also be eliminated as an area line graph for the same reason (i.e. we are not interested in a trend being observed overtime). D can further be eliminated as the Y axis says ‘number of animals’ when the question specifies that we are interested in ‘number of species’.

What are Key Things to Include in a Graph?

In the HSC, you may also be asked to draw or annotate a graph. When doing this there are a few key things you need to include to get full marks for your graph:

1. Graph title – this should state what your graph is about

2. Axis title – this should state what variable is on the axis and INCLUDE THE UNITS of your variable

3. Your scale should be increasing in consistent units

4. Use a ruler and keep your graph neat

5. Draw a line of best fit where appropriate

6. Try and make your graph as big as possible (i.e. use up the space and do not make too small)

7. If plotting multiple variables be sure to include a key

Below is an example of how you can incorporate this checklist to make a graph:

Graphic Example (for example to use in depth studies/ other written reports):

Hand-Drawn Example (for example to use in HSC/ written exams):

Conclusion

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Graph Type	Description/ When to Use It	What It Looks Like
Line	Line graphs show the relationships between different variables by showing trends over time. They are used to observe the relationship between one variable in comparison to another. They may be used, for example, to observe how much rainfalls across the different months of the year
Column	Column graphs are used to make comparisons between categories. For example, they may be used to show the different pets people have in a class.
Pie	A pie graph is useful for visualising the relationship of a variable in relation to another variable. In other words, it is a good way to present the proportional relationship of a variable with regards to other variables. For example, can be used to show the different proportion of people that like different soft drinks in a class.