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Lesson Plan
Curated OER

Tangent Lines and the Radius of a Circle

For Teachers 9th - 12th Standards
Your Geometry learners will collaboratively prove that the tangent line of a circle is perpendicular to the radius of the circle. A deliberately sparse introduction allows for a variety of approaches to find a solution. 
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Worksheet
Curated OER

Area of a Circle When Radius is Given

For Students 5th - 8th
Five problems provide practice for learners to find the area of a circle given the distance of the radius. Answers on the key use pi as a variable and do not include fully computed numeric answers. To reinforce basic multiplication facts...
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Organizer
Curated OER

Calculate the Radius

For Students 6th
In this calculating radius worksheet, 6th graders find the radius of 5 circles given the circumference information. Students must write the radius on the line provided and a box is provided to them to show their work. 
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Lesson Plan
Illustrative Mathematics

Radius of a Cylinder

For Teachers 8th - 12th Standards
Here is a multiple choice question that would make a good assessment question. Algebra learners are to look at the structure of the formula for a given radius of a cylinder and find the resulting radius when the height of the cylinder...
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Interactive
CK-12 Foundation

Restricted Domain and Range: Restricted Circle Radius and Area

For Students 9th - 12th Standards
There's no restriction to how much your class can learn about domain and range. Users of an interactive adjust the radius of a circle to see its effects on the area. They note how restrictions in the domain (radius) relate to...
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PPT
Curated OER

Size of Atoms - Trends

For Teachers 9th - 12th
This compendious collection of slides leaves no questions when it comes to the concept of atomic size. Thorough and easy-to-read graphs, tables, and graphics explain atomic radii, the shielding effect, the octet rule, isoelectric...
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Lesson Plan
Curated OER

Discovering Pi/Welcome to Pi Day

For Teachers 9th - 12th
Students explore pi. In this circle measurement lesson plan, students define and identify radius, diameter, circumference, and perimeter. Students work in groups to measure several plastic lids and record their findings. Students compare...
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Worksheet
Curated OER

Find Radius of the Circles

For Students 5th - 6th
In this finding the radius of circles worksheet, students must calculate the radius of 4 circles. Students are given diameter and must write the radius on the line for each circle. 
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Lesson Plan
Curated OER

Circumferences, Diameters, and Radii

For Teachers 5th - 8th
Students explore circumferences, diameters, and radii. In this math lesson plan, students measure circumferences in inches and compute radii and diameters, given different circumferences.
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Lesson Plan
Curated OER

Circles-Diameter, Circumference, Radius and the Discovery of Pi

For Teachers 7th
Seventh graders measure the diameter, circumference and radius of a circle and find pi using the diameter and circumference. In this geometry lesson plan, 7th graders work in groups to find the diameter, radius, and circumference of...
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Worksheet
Curated OER

Circles and Cylinders

For Students 10th
In this geometry lesson, 10th graders break down a circle and identify the different parts. They discuss chords, diameter, radius, circumference, major and minor segment. There are 42 problems broken down into 5 different sections.
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Worksheet
Curated OER

Making a Six-pointed Star

For Students 7th - 8th
In this polygon worksheet, students identify and create a six-pointed star by completing 6 steps. First, they use a compass to trace a circle with a given radius. Then, students draw a point on circumference of the circle and place the...
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Lesson Plan
Curated OER

Review Graphing Parabolas & Circles

For Teachers 8th - 12th
Students review how to graph parabolas. They practice graphing two different parabolas using the vertex and table method. They solve problems related to graphing circles, determining the radius and the center.
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Worksheet
Curated OER

Circles: Geometry Review Worksheet

For Students 10th Standards
Tenth graders solve and complete 14 different geometry problems. First, they find the area and circumference of a circle with a given radius. Then, they find the area between a circle and an inscribed equilateral triangle given the...
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Lesson Plan
National Research Center for Career and Technical Education

Transportation, Distribution, and Logistics: Tire and Wheel Assemblies

For Teachers 6th - 12th Standards
Is bigger really better? By the end of this lesson, learners will be able to apply formulas for computing the diameter of tires and wheel assemblies. Begin by showing a slide presentation that will review definitions for radius and...
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Worksheet
Curated OER

Calculate the Radius

For Students 6th - 12th
In this radius worksheet, students calculate the radius of a circle when the area is given to them. Students complete 5 problems total.
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Interactive
CK-12 Foundation

Distance Between Two Polar Coordinates: Exploring Changes in Angle and Radius

For Students 10th - 12th Standards
Get straight answers on a curved grid. An interactive has learners apply the Law of Cosines to find the distance between two points on the polar coordinate plane. The pupils use the radii lengths and the angle between the two radii to...
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Lesson Plan
Curated OER

Finding The Circumference Given The Radius

For Teachers 6th - 7th
Students develop an understanding of pi and the relationship between the diameter, radius and circumference. After a lecture/demo, students use construction paper and a compass to solve problems using diameter, radius and circumference.
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Interactive
Curated OER

Circle Problems - Radius, Diameter, Circumference and Area

For Students 9th - 12th
In this online math worksheet, students determine the radius, circumference, diameter and area of circles. This excellent resource allows the students to check their answers, and to get "hints" should they run into difficulties. A...
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Lesson Plan
Curated OER

Circumference, Diameter, Radius

For Teachers 6th
Sixth graders will determine the circumference, diameter, and radius of a circle. In this circle lesson plan, 6th graders will measure the appropriate amount to find these measurements on circles.
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Interactive
Curated OER

Find the Radius of the Smallest Circle that Contains the Figure

For Students 9th - 10th
In this geometry worksheet, students calculate the radius of the smallest possible circle that contains the figure provided.  The complete solution is provided by clicking on the "show solution" button found below the problem.
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Lesson Plan
Curated OER

Radius, Diameter and Area

For Teachers 8th - 9th
Young scholars identify the radius and diameter of a circle. In this geometry lesson, students calculate the volume and area of a cylinder and circle. They relate the circumference of a circle to Pi.
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Worksheet
Curated OER

Circle Formulas

For Students 10th
Tenth graders apply various circle formulas to determine radii, diameter, circumference, area, arc length, and sector area. The two page activity contains twenty-five problems. Answers are not provided. 
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Lesson Plan
Curated OER

Exploring Circles

For Teachers 9th - 12th
Students explore circles using a graphing calculator. In this circles lesson, students write the equation of a circle with a given center and radius length. Students find the most appropriate model for each combination of data they...

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