Circle Graphs/ Pie Charts

[NEB]

Is this the intended domain for circle graphs?  Are we supposed to see that as part of percents?  Or would the circle graph/pie chart be part of statistics or probability model?

[Bill McCallum]

Circle graphs are not explicitly mentioned in the standards; categorical data is represented by bar charts, which are introduced in Grade 2. A reason is that the connection with the number line is tighter for bar graphs, since the value in each category is read from the vertical scale, rather than estimated from the area of a sector.

[NEB]

So where and when do the standards suggest circle graphs be taught?  They are certainly a part of daily life and students must understand what they represent.

I agree that bar graphs are wonderful and have a tight connection with the number line.  Circle graphs are really nice to quickly view relative size compared to the whole.  That is the reason they are used so often in newspapers and daily periodicals.  They display information in a format easy for people to digest.

So, where should they be taught?

I value your insight and look forward to your guidance.

 

[Bill McCallum]

The standards don’t suggest circle graphs should be taught anywhere, although of course they also don’t forbid the teaching of circle graphs at some point, as long as it doesn’t interfere with the things they do suggest. I agree they are a part of daily life, but I worry a bit about the statement that “students must understand what they represent.” Yes, eventually, perhaps during their schooling, perhaps after. But this sort of rhetoric is what led us into the mile-wide-inch-deep curriculum. There are many wonderful and important things to learn; not all of them can be learned before the end of high school. Focus is important for depth.

Another point to consider is that not every important quantitative representation has to be taught in mathematics class. Circle graphs could show up in history, social studies, or science.

[Author]

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