Grappling with Graphs

How many times have we become frustrated when carrying out a graphing activity in lessons? In this session we examined some of the research around graph interpretation and explored how to develop student understanding.  

It takes an expert approximately the same amount of time to interpret a graph as it does to interpret a paragraph of text, around 30 seconds. This time is spent thinking about and interpreting the line of best fit, relating it to the labels on the axes and any other information. How might this be different for our students? Do we provide them with enough time to read and interpret graphs?  

One piece of research used eye-tracking software to find out how the approach to graph interpretation differs between novices and experts. Whilst experts analysed the contextual information first, focusing on the labels, units, title and key before looking at the line of best fit. Novices often looked for clues in the question stem and then went directly to the line of best fit, ignoring the contextual elements. This might explain why students say ‘it goes up’, when asked to describe the trend on a graph. They are not making use of the labels on the axes and other information to inform their descriptions.  

Another reason students find the interpretation of line graphs difficult is because they ignore or are unable to interpret the variable plotted on the x-axis. This difficulty can arise because the two ends of the line of best fit form a visual chunk which appears to be ‘floating’ and detached from the x-axis. It is easier for students to interpret bar charts as the bars form a visual chunk in physical contact with the x-axis, so the eye is drawn down towards the labels. 

What are the implications of the outcomes of this research for us as teachers? We might assume that students develop graph interpretation skills through exposure to graphs, but evidence suggests this is not the case. Graphing needs explicit teaching. 

Amanda and Karen have explored the research surrounding graph interpretation and construction in their book Grappling with Graphs. This handy book summarises the research surrounding graphing, and provides practical resources to download and use in the classroom. Grappling with Graphs can be purchased from the Millgate House website: https://www.millgatehouse.co.uk/product/grappling-with-graphs/