Quick Tip: Choosing the right graph

April 6th, 2010

Graphs can be a wonderful tool for teaching students to think visually. And just as we teach students that different words convey different meanings, we can guide students to think about the different relationships and ideas conveyed by, say, a line graph vs. a bar graph or a pie chart. In I See What You Mean: Children at Work with Visual Information, Steve Moline discusses the importance of choosing the right graph as well as effective ways to introduce the graphs to students. 

In introducing graphs to students, allow them to design all aspects of the text.  This means it is better to hand the students a blank page rather than a sheet of “graph paper”.

1.You can use a graph to present information when you want to compare quantities.  Don’t make a blank graph sheet for them “to fill in”.  Let the children design the graph.

2.You can work on a graph over different time periods:  

  •  in one session (what we ate yesterday)
  • over a week, adding a little each day (weather details)
  • over a longer period (“how many of our seedlings grew leaves?”).

3.The graph can be made in different ways: 

  • on a large sheet of paper, scribed by the teacher during a class discussion in which everyone contributes
  • different children add a piece of information each day to the one graph
  • pairs or individuals make lists and later they compile them into one graph….

“Which graph should we use?”

Different kinds of graphs — column, line or pie — compose the same information with different (sometimes unintended) meanings.  Choosing an inappropriate graphic text to express the data can have the effect of sometimes misleading or confusing the reader. 

For example, in one grade 5 classroom, the students were discussing favourite TV programs and commercials as a whole-class activity.  The data was scribed on a large sheet of paper by the teacher in the form of a simple bar graph, using labels and counting marks:

 

The students were then asked to design another kind of graph which recomposed this data.  In Warren’s pie graph of this information (Fig. 9) the data has been recomposed as wedges of pie.

 

Warren has performed some computations to get to this point, since the total number of preferences (30) divided by the degrees of the circle (360) needed to be multiplied by the “score” for each program.  A protractor was then used to measure the units of the circle for each wedge of pie.  The actual scores out of 30 were also added to the text as labels (such as “Coca Cola 8”); these labels work as a parallel expression in words and figures of the same data expressed graphically in the pie wedges.

On the other hand, Chantal and Bianca chose to recompose the same information as a line graph (Fig. 10).

 

Whereas the intention of the text is clear, the continuous line that moves across the graph from left to right suggests a continuity through the data that does not exist.  There is no actual process or sequence represented by this line.  The information would have been presented without this misleading element if the line were replaced by a separate column for each label (as in Fig. 2, page 68), since there is no particular significance in the order in which these labels have been placed from left to right across the text.

 

Moline also discusses other types of graphs as well as time lines, maps, and tables.

Entry Filed under: Literacy,Quick Tip Tuesday

1 Comment Add your own

  • 1. Gresham  |  April 8th, 2010 at 6:41 pm

    Each week in my classroom, two students sign up to complete a survey. They develop a question, collect data from their classmates, and then create a graph to communicate their results. My 4th graders love learning more about each other, and they’ve become pretty good at creating graphs. Most of my students create bar graphs or venn diagrams – this post has reminded me to show students how effective circle graphs can be.

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