Illuminations
Circumference and Areas of Circles
Middle and high schoolers listen to a scenario about a puppy and use the scenario to develop formulas in order to find the area of a circle. In this circumference instructional activity, pupils understand how to find the radius,...
Curated OER
Area of Circles and Probability
Students investigate the area of squares and circles. In this geometry lesson, students calculate the area and probability of simple events. They work on a laptop using Safari.
Illustrative Mathematics
Eight Circles
We are used to finding the area of a circle by plugging the radius into an equation. Here, learners are required to go further to find multiple areas and calculate the difference. They must detect a pattern in order to figure out the...
Flipped Math
Circles and Arc Lengths
Discuss all things round and round. Pupils review finding area and the circumference of circles and use them to solve problems. Next, they learn about central angles and their relationships to measures of arcs. Learners then find out how...
Willow Tree
Area of Common Geometric Figures
Scholars can use area formulas, but can they apply what they know about area? The lesson plan challenges learners to think logically while practicing finding area of shapes such as rectangles, circles, parallelograms, triangles, and...
Mathed Up!
Area of Sector and Length of Arcs
Viewers learn how to apply proportional reasoning to find area of sectors and arc lengths with a video that starts off explaining how to find the areas of circle sectors and the lengths of arcs. Scholars then practice solving problems...
Curated OER
Areas of Geometric Shapes with the Same Perimeter
A triangle, square, hexagon, and circle all have a perimeter of one unit. Eighth graders must attempt to find the area of each and arrange them in order from least to greatest areas. A terrific task for applying four different area...
Texas Instruments
Area of Circles
Students explore circles. In this algebra/geometry lesson, students discover the formula for the area of a circle, as they investigate the ratio of the area of a circle to the radius^2.
Curated OER
Calculate Area Using Pi
Geometers find the area of four circles given their circumferences. Circumference is presented in the form of "numeral (diameter) x pi"; the answer key shows solutions as "numeral (radius squared) x pi," so computation is limited to...
EngageNY
Proving the Area of a Disk
Using a similar process from the first lesson in the series of finding area approximations, a measurement resource develops the proof of the area of a circle. The problem set contains a derivation of the proof of the circumference formula.
Mathed Up!
Area and Circumference of Circles
Don't go around and around, help your class determine amounts around and in a circle with a video that connects circumference to the perimeter or the distance around an object. The resource includes 14 questions dealing with circles and...
Illustrative Mathematics
Stained Glass
A complex question looking for the total cost of a stained glass window by calculating area and circumference of a circle. With detailed components, this activity will challenge your designers to figure out if they have enough money to...
Virginia Department of Education
Arc Length and Area of a Sector
What do skateboarding and baked goods have in common with math? You can use them to connect half-pipe ramps and cakes to arcs and sectors. Pupils compare the lengths of three different ramp options of a skate park. They calculate the...
EngageNY
Unknown Length and Area Problems
What is an annulus? Pupils first learn about how to create an annulus, then consider how to find the area of such shapes. They then complete a problem set on arc length and areas of sectors.
Curated OER
Area of Circle Worksheets
In this geometry learning exercise, 10th graders calculate the area of circle give either the radius or the diameter. The one page interactive learning exercise contains ten questions. Answers and hints are included.
Curated OER
Circle Formulas
Tenth graders apply various circle formulas to determine radii, diameter, circumference, area, arc length, and sector area. The two page worksheet contains twenty-five problems. Answers are not provided.
Curated OER
Similar Triangles and Trapezoids, and Circles
High schoolers answer two problems involving area of shaded regions. Students then answers six questions involving perimeter, area, and circumferences. The remaining two questions involve ratios of similar figures.
Inside Mathematics
Circles in Triangles
Challenge the class with inscribed circles in triangles. The assessment task requests class members use their knowledge of circles and right triangles to prove two triangles are congruent. They go on to utilize their knowledge of...
Curated OER
Circle Problems - Radius, Diameter, Circumference and Area
In this online math learning exercise, 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....
Mathematics Assessment Project
Calculating Arcs and Areas of Sectors of Circles
Going around in circles trying to find a resource on sectors of circles? Here is an activity where pupils first complete an assessment task to determine the areas and perimeters of sectors of circles. They then participate in an activity...
Flipped Math
Sectors and Segments
It's a piece of pizza! Pupils learn about a sector of a circle as a slice of the circle and determine how to find its area. Scholars continue to find out how to calculate the segment of a circle based on the sector's area. At the end,...
Mathematics Assessment Project
Solving Problems with Circles and Triangles
After completing a task involving examining the ratio of areas of triangles and circles in a given figure, scholars examine sample responses to identify other strategies they could use to solve the problem.
EngageNY
What Is Area?
What if I can no longer justify area by counting squares? Lead a class discussion to find the area of a rectangular region with irrational side lengths. The class continues on with the idea of lower approximations and upper...
Curated OER
Finding PI
Students select and use appropriate operations, methods and tools to compute or estimate using whole numbers. They develop and use formulas for determining the circumference and area of circles. Students determine and describe the...