What is a Circle?
Basics on the topic What is a Circle?
Attributes of Circles
Circles all have a round shape and all have certain attributes. In this text you find the answer to the question ‘what are the characteristics of a circle?’ as well as information about defining and nondefining attributes of circles.
Attributes of Circles – Definition
What are attributes exactly? Attributes are characteristics that shapes have to help us put them into categories. A square for example has four sides which can be called a square’s attribute. Attributes of circle can either be classified as defining or nondefining.
Attributes of Circles – Defining Attributes
A curved line that is round, has no sides, no corners, and an equal distance from the center is a circle.
Attributes of Circles – Non Defining Attributes
A circle can be any size, color or face in any direction.
Attributes of Circles – Additional Practice
These are the defining and nondefining attributes of circles:
Category of attribute  “A circle …” 

defining  is round, has no sides or corners. 
nondefining  can be of any size, color and face in any direction. 
Are the shapes below examples of circles? Use the defining and nondefining attributes to determine whether a shape is a circle or not.
After watching the video, you can practice describing the attributes of circles using our interactive exercises and worksheets for grade 1.
Transcript What is a Circle?
“Nico, look at all those fun prizes in that machine!” “Do you think you can pick one up with the claw?” “Looks tricky, (...) but let’s give it a try!” Nico pulled two prizes out of the claw machine. A play clock... and a frisbee. “These two prizes are different, but the outside shape of them look the SAME!” “Yes, they are both round!” “Let’s make the claw machine even trickier by trying to get more prizes that have a round shape!” "Circles" Shapes are twodimensional figures that we can name based on their "defining attributes". Defining attributes are characteristics that a shape MUST HAVE. Let’s look at a circle. The defining attributes of a circle are that it must be a closed shape that has… A curved line that is ROUND, ... No sides,... And no corners. A circle also must be the same distance from the center all the way around. If defining attributes are characteristics a shape must have, what are NONdefining attributes? A NONdefining attribute is something that a shape has, but doesn’t always have to be the same. Size is a nondefining attribute. A circle can be big(...), big,(...) BIG… or a circle can be small,(...)small,(...)_ small. Color is another nondefining attribute. Circles can be ANY color! Circles can also face many different directions. No matter how you turn it, a circle always looks the SAME! Let’s identify circles. Is this a circle? Start by looking at the shape. Is it a closed round shape made with a curved line? Yes, it is a closed round shape made with a curved line. Does it have sides? No, it doesn’t have any sides. Does it have corners? No, it doesn’t have any corners. Is there an equal distance around from the center? Yes, there is an equal distance around the center. This is a circle. Let’s try this one. Is this a circle? Is it a closed round shape made with a curved line? Yes, it is a closed round shape made with a curved line. Does it have sides? No, it doesn’t have any sides. Does it have corners? No, it doesn’t have any corners. Is there an equal distance around from the center? No, this shape is NOT an equal distance around from the center. This shape is NOT a circle. Now that we know all the attributes of a circle, let’s see if we can help Nico and Nia find more prizes that have a circular shape. Look at the claw machine. Can you point to other prizes that have the outside shape of a circle? Here’s one! (...) This stuffed cookie! This ring also makes the shape of a circle. And here's ONE more (...) this sparklingly golden yoyo! Remember, (...) Shapes have defining and nondefining attributes. A circle is a closed round shape that is made with a curved line. It doesn't have any sides or corners... but, it must be equal distance all the way around the center. A circle can be any size,... or color, ... and face in any direction. Nico and Nia see they have ONE token left. They can only go after one more prize! I REALLY hope we get the golden yoyo, Nico!" "YAY!" "YAY!"
What is a Circle? exercise

Recognizing circles.
HintsRemember that a circle has to be the same distance from the center all the way around. Here is an example.
Remember, circles must be closed shapes with one continuous curved line.
Is the shape the same distance from the center to the edge, all the way around? This example is not a circle.
SolutionThe drawings of the pizza and the orange slice are circles.
The other images are not because a circle must be a closed shape, it must be the same distance from the center all the way around and be made from one continuous curved line.

What is a circle?
HintsTo draw a circle, do we use a curved or straight line?
Sides are made from straight lines, not curved.
Solution A circle must be made from one continuous curved line all around.
 The number of sides a circle has is always 0.
 A circle must be the same distance from the center to the edge, all the way around.
 A circle is a flat 2D shape that is closed.

True or False?
HintsWhich of these is a circle?
Are these all circles?
SolutionFour of the statements are true and three of the statements are false.
Some of the correct statements are about defining properties (it must be a closed shape) and some of the statements are about nondefining properties (a circle can be any size or color).

How many circles are there?
HintsRemember that circles have to be the same distance from the center all the way around.
Remember that circles can be any color and have any pattern on them.
SolutionThere are 3 circles in this image.
These are the only shapes in the image that:
 Have one continuous curved line all the way around
 Are closed shapes
 Have the same distance from the center to the edge all the way around

Looking for circular toys.
HintsDoes the shape have one continuous curved line all the way around?
Is the toy the same distance from the center to the edge all the way around?
There are three circular toys to find in total.
SolutionThere are three circular toys: The cookie, the doughnut and the fidget toy.
These are circles because they:
 Are made from one continuous curved line
 Are closed shapes
 Are the same distance from the center to the edge, all the way around

Finding circles in real life.
HintsThe face of the shape is a circle if it is made up of a continuous curved line and is the same distance from the center to the edge all the way around.
Imagine looking at the object from above, do any of the faces look like a circle?
Solution The ice cream cone is a cone and has one circular face.
 The baked beans can is a cylinder and has two circular faces.
 The book is a rectangular prism and has no circular faces.
 The pyramid has no circular faces.
 The drum is a cylinder and has two circular faces.
 The gift box is a cube and has no circular faces.
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