Calculator Soup
Calculator Soup: Sphere Calculator
This online calculator will calculate the 3 unknown values of a sphere given any 1 known variable including radius r, surface area A, volume V and circumference C. It will also give the answers for volume, surface area, and circumference...
Ministry of Education and Universities of the Region of Murcia (Spain)
Ministerio De Educacion Y Ciencia: Circunferencia Y Circulo: Longitudes Y Areas
Reinforce your knowledge of the circumference and the area of a circle with these activities. [Requires Java.]
PBS
Pbs Learning Media: Formulas: Targeted Math Instruction
At the end of this lesson plan about formulas, students will be able to identify and apply the correct formula for a given situation, solve for any unknown component of the formulas for perimeter, circumference, and area of regular and...
Learning Wave Communications
Learning Wave: Geometry, Section 2
Geometry concepts are briefly discussed at this site, including volume of a cylinder, parallelograms, circles, trapezoids, and triangles. Sample problems and applications are included for practice.
BBC
Bbc: Bitesize Review Circle Introduction
Do you need to learn about Pi, circumference, or the area of a circle or just have a quick refresher about them? This British web site will take you through the basics and offers a quick on-line test to help you check your understanding.
Discovery Education
Discovery Education: Web Math: Find Out Things About Circles
This WebMath site will assist with finding the radius, diameter, circumference, and area of a circle.
Khan Academy
Khan Academy: Praxis Core Math: Circles Lesson
A basic review of circles and how to calculate the circumference, radius, diameter, and area. Includes practice questions.
Texas A&M University
Wtamu Virtual Math Lab: Beginning Algebra: Formulas
This tutorial will show you how using formulas can help you solve problems. Include formulas for various geometric shapes and steps showing how to use them.
Other
Allmath: Math Glossary
Are your students having difficulty understanding math terminology? Try this A-Z glossary on math related terms. It's quick, easy to read, and very complete.
National Council of Teachers of Mathematics
The Math Forum: Elementary Geometry Circles
The Math Forum offers an archive of question and answer sessions on circles and how they relate to geometry.
Math2
Math2: Circles
This site has many useful formulas and examples relating to circles, including related definitions, circumference of a circle, area of a circle, length of a circular arc, area of a circular sector, equation of a circle in cartesian...
Alabama Learning Exchange
Alex: Circling Around
Students will calculate the diameter, circumference, and ratio of a real world object. Students will create an electronic slideshow to illustrate the process of determining the diameter, circumference, and ratio of these objects.
Cuemath
Cuemath: Radius
This reference tool explores the radius of a circle. Provides definitions, solved examples, and practice questions with answers.
National Council of Teachers of Mathematics
Nctm: Figure This: Math Challenges for Families
Students, teachers, and parents alike will enjoy this challenging math site. It contains a clever brain teaser section plus creative problems related to algebra, geometry, measurement, numbers, statistics, and probability. A Spanish...
National Council of Teachers of Mathematics
The Math Forum: Multicultural Math Fair: Srinivasa's Spheres
Straightforward lesson plan that introduces learners to pi by letting them measure real objects and solve a challenge problem. Includes instructions and a "Data Sheet" for keeping track of measurements. Available in English and Spanish.
Common Core Sheets
Common Core Sheets: Geometry 8.g.3 Worksheets: Coordinate Plane
Worksheets provide practice with finding the area or circumference of a circle and answer keys are provided. You can even create your own worksheet or flashcards.
Mocomi & Anibrain Digital Technologies
Mocomi: What Is Circle?
Discusses the radius, diameter, circumference, and area of a circle.
Curated OER
Web Math: Find Out Things About Circles
WebMath offers a great site for students to practice finding the diameter, area and circumference of a circle.
Texas Instruments
Texas Instruments: Circle Around
In this activity, students compute the circumference and area of circles. They understand that the ratio of the circumference to the diameter is a value called pi. [Requires Adobe Reader.]
PBS
Pbs Mathline: Bubble Mania [Pdf]
Bubble Mania is a lesson plan that focuses on the concept of measurement as it applies to the diameter, circumference, and area in a bubble. Extension activities and connections, related worksheets, and additional resources are included.
University of North Carolina
A Dictionary of Units of Measurement
This site contains an extensive list of various units of measurement known internationally and across several disciplines. Unit symbols are also included.
Saddleback College
Algebra2 Go: Prealgebra
The resource consists of comprehensive learning tools such as class notes, video lectures, and templates through which students can review prealgebra topics.
Math Open Reference
Math Open Reference: Radius of a Circle
Learn about the radius of a circle with this useful reference guide. Provides a detailed definition, examples, and an interactive activity that enhances further explanation. Includes links to related topics.
Math Open Reference
Math Open Reference: Diameter
A complete reference guide to diameters. It provides definitions, examples, and interactive activities that enhance further explanation. Includes links to related topics.