Circle Graphs have my Students' Heads Spinning!
Date: Around 1993
I am currently in a teaching program. Last week I began a part
of my practicum that has us teaching one lesson per week in the assigned
school. My cooperating teacher asked me to introduce circle graphs to her
sixth graders. She told me the students were familiar with the process of
converting fractions to decimals and vice versa. One third of the way through
my lesson, I realized the majority of the students had no concept of how to do
this. I retaught the conversion process and then again had them look at
circle graphs, yet they still remained confused. How can I better illustrate
the circle graph concept and even the fraction to decimal conversion so my
future students will understand? Any suggestions will be greatly appreciated.
Thank you for your time, and I apologize for the lengthy scenario before my
I believe a circle graph is just a pie chart showing a fraction
so a pie cut once through the middle demonstrates 1/2 = 0.5, etc. As for the
fraction to decimal conversion, I cannot think of any methods other than the
plain old fashioned long division. Of course, once you know that 1/8 = 0.125,
then you know that 3/8 = 3 * 0.125 = 0.375 without having to do the long
division. Hope this helps!
Hawley's hint about how to use 1/8 to get 3/8 is a nice use of
pattern matching. But fundamentally, how will the students understand the
"circle graph" idea? Basically, it is better to describe it as a pie chart
because then students can visualize cutting it up just as if it were a pie.
One way to get the concept across might be to cut up some cardboard "pies"
into pieces; cut up one into thirds, one into fourths, fifths, eighths, and so
forth...another would be to split up into groups of 5, hand each group a pie,
and tell them to draw a piece of paper from a hat. One piece of paper would
say 3/8 and the rest would say 1/8. Or, better yet, one could say 0.375 and
the others 0.125. Then have them divide up the pie (or pizza) according to
the numbers they drew. Hope this helps.
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Update: June 2012