Proportionality between circumference, angle and arc length; area, angle and area of sector. Circumference and area of circle equation, Image of four circles with hotpots of calculations

Angle of sector or arc is proportional to the circumference or area of total circle. Interactive drag and drop factor to use when calculating arc length or sector area.

The Greek mathematician Archimedes approximated pi by inscribing and circumscribing polygons about a circle and calculating their perimeters. Similarly, the value of pi can be approximated by calculating the areas of inscribed and circumscribed polygons. This activity allows for the investigation and comparison of both methods.

This lesson is Day 11 in a series of 12 lessons around fraction equivalences and comparisons.

This video lesson reviews parts of a whole, comparing fractions, and equivalent fractions. No materials are needed.

This lesson is Day 2 in a series of 12 lessons around fraction equivalences and comparisons.

This video lesson uses paper folding to introduce the concept of equivalent fractions. To complete this lesson, make sure you have a square piece of paper (any size) and a crayon

This lesson is Day 2 in a series of 12 lessons around fraction equivalences and comparisons.

This video lesson introduces the idea that fractions can be used to represent 1 whole. To engage in this lesson, students may use virtual circle models from Toy Theater (https://toytheater.com/fraction-circles/)

This lesson is Day 4 in a series of 12 lessons around fraction equivalences and comparisons.

This video lesson looks at how we use fractions in the kitchen. Students are challenged to use circle models to find equivalent fractions for a recipe. Students may use virtual circe models from the Toy Theater (https://toytheater.com/fraction-circles/).

The purpose of this task is to strengthen students' understanding of area. It could be assigned in class to individuals or small groups or given as a homework exercise to generate interesting discussions the following day. The relatively high levels of complexity and technical demand enhance its instructional value.

This lesson unit is intended to help teachers assess how well students are able to solve problems involving area and volume, and in particular, to help you identify and assist students who have difficulties with the following: computing perimeters, areas and volumes using formulas; and finding the relationships between perimeters, areas, and volumes of shapes after scaling.

This lesson unit is intended to help teachers assess how well students can: Understand the concepts of length and area; use the concept of area in proving why two areas are or are not equal; and construct their own examples and counterexamples to help justify or refute conjectures.

Students select three different rectangles and determine the number of color tiles needed to cover them. Students sketch and label the rectangles in order from least to greatest area and complete sentence stems about the rectangles.

A structured geometry program teacher edition of daily lesson plans and teacher supports to accompany the College Access Reader: Geometry student edition.

In this lesson students determine the area of a rectangle with fractional side lengths. Students explore the idea of doubling a side and the impact that has on the area. 

This resource demonstrates the distributive property through the area of rectangles. You can manipulate the dimension by moving the slider.

CK-12 Foundation's Geometry FlexBook is a clear presentation of the essentials of geometry for the high school student. Topics include: Proof, Congruent Triangles, Quadrilaterals, Similarity, Perimeter & Area, Volume, and Transformations.

CK-12's Geometry - Second Edition is a clear presentation of the essentials of geometry for the high school student. Topics include: Proofs, Triangles, Quadrilaterals, Similarity, Perimeter & Area, Volume, and Transformations.

CK-12's Texas Instruments Geometry Student Edition Flexbook is a useful collection of exercises intended to enrich a student's understanding of basic geometric principles.