What Is a Circle?

24 Mar

After reading a blog post What is a Circle that was linked to another blog post What’s in a circle, I asked my students what is a circle.

Screen Shot 2014-03-10 at 8.27.12 PM

rounded figure, no straight lines except the diameter, always 360°      1

A round 2D shape whose components are radius, diameter, and circumference. Its measure is 360 degrees, and other factors can be found with its components.         1

a regular geometric figure whos area is multiplied by pi            1

a geometric shape that is always symetrical and the ratio between its diameter and circumference is π.    1

a bunch of points that have same distance from a point which is center          1

a polygon that has no angles.          1

geometric shape that has no edges or angles and has a diameter and radius. 1

A round 2D figure that has an equidistance from any point on the circle to the center… a.k.a. constant radius       1

A round shape that curves in a consistant, unchanging motion until it reaches its starting point.     1

a round shape that has a diameter and radius that are used to find the area and circumference    1

a geometrical shape containing chords,diameters, radii, and right triangles, all composed in 360 degrees  1

a geometric figure from whose center all lines drawn to the outside are equivalent  1

a shape thats lines from the center to the edge all have equal distance           1

A closed shape with no straight edges in which a line drawn from the center to a point on the shape will always have the same distance.       1

x^(2)+y^(2)=36       1

a shape made up of points equal distant from a point    1

a shape that is round and measures to be  360°  1

a 2D round shape     1

a shape wiith no angles (corner) and an area of 360      1

area of πr^(2)           1

a geometric shape     1

a shape with no straight lines and all the lines that are drawn from its center to the outside are equal      1

a geometric shape with no sides or straight lines 1

a polgon with infinite lines of symmetry    1

a shape that all points are equal distance from the center         1

It is a geometrical shape without any corners.      1

A circle is a smooth figure that has no sides and contains a diameter,radius, and several arcs. It is always symetrical.      1

figure with rounded edges with a total of 360° and has an equal diameter all the way around       1

a shape with infinate points and no sides, just a constant curve connected.     1

a round shape that has an equal radius all around the center of that shape.  1

a 2d shape with a curved line that is 360 degrees           1


There was apparently too much time between my reading the post and my sending the question to my students. Because I completely forgot what was suggested to do with the results. I ran across the blog post again a few days later, so on our second day of circles in the coordinate plane, I gave a few of the definitions students had submitted & asked students to try to “break” the definition with a figure that met the requirements but wasn’t actually a circle.

Screen Shot 2014-03-23 at 7.20.45 PM

We are beginning to see the importance of attending to precision, not just with numerical solutions but also with our language.

I really like the idea to have students come up with a definition alone first – and then within groups before sharing with the whole class. And so I’m glad that the journey will continue next year, when I get a do over …

1 Comment

Posted by on March 24, 2014 in Circles, Geometry


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One response to “What Is a Circle?

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