Background Information for Teachers
The circle holds few mysteries for the teacher—at least when we are teaching
its measurement and general properties. But as you work through the
Activities section with your class, you may find you are asking
yourself, What are the underpinnings of the area and circumference formulas?
How did pi appear on the scene? What is the value of rotation symmetry in the
big mathematics picture? The resources below, developed for teachers, offer not
only information but also online exercises that will involve you in answering
your questions.
Pi is central to the formulas for circumference and area. These activities,
intended for K-8 teachers, explore the formulas.
This is a chance to "play" online with dynamic software. You will construct
figures and discover properties of parallel lines and circles. The lesson,
created for K-8 teachers, includes the formal geometric definitions, but the
emphasis is on investigating relationships among the geometric figures.
What is rotational symmetry, and why is it important? In this session, developed
for K-8 teachers, you can find the answers. Using this symmetry, you will
create designs and consider their properties. A video segment shows teachers
determining rotational symmetry.
This article gives valuable background information about Eratosthenes' ingenious
method for measuring the circumference of the Earth.
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Copyright
June 2006 — The Ohio State University. This material is based upon work
supported by the National Science Foundation under Grant No. 0424671. Any
opinions, findings, and conclusions or recommendations expressed in this
material are those of the author(s) and do not necessarily reflect the views of
the National Science Foundation.
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This work is licensed under a
Creative Commons License.
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