Circumference (It Just Makes Sense)

Lyrics

Chorus
If I need to measure up a clock (circumference)
Measure the post on a dock (circumference)
If I’m buying rims for a car (circumference)
Hey, yo, 2πr! (It just makes sense)
If I need to measure up a hat (circumference)
Spinnin’ records like that (circumference)
If I need to pick the right jar (circumference)
Hey, yo, 2πr! (It just makes sense)

Verse I
Check out and see all the round things you can find
So many circles out there, it will blow your mind
It can be hard to measure distance around
But once you use a little math you can figure it out
If you need to find the distance around a circle shape
All you need is one formula and a measuring tape
Then you measure up the radius so you can figure out
‘Cause twice that radius times π is what a circle’s all about

Chorus

Verse II
You know that every circle—if it’s big or little—
Has one single point that’s right in the middle
So you start on one edge, draw a straight line
Right through the center and to the other side
That’s the diameter. And half of that is the radius
That’s the crucial number that we need to figure this out
Then we multiply it by 2π
Circumference, 2πr, there’s no need to ask why

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Description

This song teaches the formula for the circumference of a circle using pi and the radius. It introduces many examples of circular objects where the formula could be used including a clock, car rims, or a jar. "Circumference (It Just Makes Sense)" also explain what the diameter and radius are and how to measure both variables. There are teaching materials at the bottom of the page, including worksheets, lesson plans, activities and games which are resources for teachers and homeschool parents to generate teaching ideas for the song topic. Students will have a better understanding of how to find the circumference of a circle using the formula 2 x pi x r.

This math song is suitable to help teach the circumference formula to elementary school students (4th grade, 5th grade and 6th grade), middle school, high school, home school, and college classes.

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Related Reading and Activities

Reading

Education World
Explain Adding and Subtracting Fractions
This website explains how to add and subtract fractions, and provides links to other helpful resources on the topic. The site is extensive and has worksheets and games in addition to excellent information. Excellent resource.
Grades 3-8

The Math Page
Multiply and Divide Fractions
Using examples, this site explains how to multiply and divide fractions.
Great detail in the explanation will help students who have a difficult time understanding. This is a good exercise for students with problems multiplying or dividing fractions. There are many great lessons on this site!
Grades 5-8

Lesson Plans & Activities

ABCTeach
Worksheet: Fraction Addition – Unlike (Set 1) (PDF)
Worksheet: Fraction Addition – Unlike (Set 2) (PDF)
Worksheet: Fraction Division – Unlike (PDF)
Worksheet: Fraction Multiplication – Unlike (Set 1) (PDF)
Worksheet: Fraction Multiplication – Unlike (Set 2) (PDF)
Worksheet: Fraction Subtraction – Unlike (Set 1) (PDF)
Worksheet: Fraction Subtraction – Unlike (Set 2) (PDF)
These worksheets allow students to practice subtracting and reducing unlike fractions. Bare bones worksheets, but get the job done. Can be easily downloaded and reprinted.
Grades 4-8

AtoZTeacherStuff
Fractions in Everyday Life
This activity uses household objects (measuring spoons, cups, etc) and a recipe which they double and multiply out even farther to show students how fractions are relevant in our everyday lives. Recipe with lots of fractions included. Could be fun.
Grades 3-8

Education World
Equivalent Fraction Bingo
This bingo game gives students practice in understanding the concepts of numerators and denominators. This could be fun! The bingo grid, fractions for the card and flash cards are all included. Easy to put together and use.
Grades 3-8

Slicing Up Fractions
Students review the concepts of equivalent fractions, adding fractions, and multiplying fractions as they solve problems involving pieces of pizza. Thorough and visually rewarding. Excellent as introduction to fractions or for younger students.
Grades 3-8

Math Forum
A Tour of Fractions
This collection of fractions lesson plans has a wide array of variety, from activities to reference materials. Lots of resources here on a variety of levels.
Grades 3-8

SCORE Mathematics
Pumpkin Pie for All!
This is a link to the quintessential pie/fraction lesson. California State standards are listed at the end.
Grades 2-8

Media

Math Playground
The Boston Marathon (video)
This animated video takes students on a step-by-step journey of figuring out a fractions problem about a runner’s speed when running the Boston Marathon. This is a fun site with other math games and puzzles too.
Grades 4-8

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State Standards

State standards listed here are representative of school standards across the United States.

California

6th Grade
Measurement and Geometry: 1.1 - Understand concept of constant such as π; know formulas for circumference/area of circle.
Measurement and Geometry: 1.2 - Know common estimates of π (3.14; 22⁄7) and use these values to estimate and calculate the circumference and the area of circles; compare with actual measurements.

7th Grade
Measurement and Geometry: 2.1 - Use formulas routinely finding perimeter/area of basic two-dimensional figures and surface area and volume of basic three-dimensional figures, including rectangles, parallelograms, trapezoids, squares, triangles, circles, prisms and cylinders.
Measurement and Geometry: 2.3 - Compute length of perimeter, surface area of faces, volume of three-dimensional object built from rectangular solids. Understand when lengths of all dimensions are multiplied by scale factor, the surface area is multiplied by square of scale factor and volume is multiplied by cube of scale factor.

Florida

6th Grade
G.4.1 - Understand concept of pi, know common estimates of Pi (3.14; 22/7) Use values to estimate/calculate circumference/ area of circles.

Massachusetts

5th & 6th Grades
6.M.5 - Identify/measure/describe circles and relationships of radius/diameter/circumference/area (e.g., d = 2r, p = C/d), and use concepts to solve problems.

7th & 8th Grades
8.M.3 - Demonstrate understanding of concepts. Apply formulas/procedures for determining measures, including area and perimeter/circumference of parallelograms/ trapezoids/circles. Given formulas, determine surface area/volume of rectangular prisms/cylinders/spheres. Use technology as appropriate.

New York

6th Grade
6.G.7 - Determine area/circumference of circle, using the appropriate formula.
6.G.9 - Understand relationship between circumference and diameter of circle.

7th Grade
7.G.1 - Calculate radius or diameter, given circumference or area of circle.

Texas

6th Grade
6.8.A - Estimate measurements (including circumference). Evaluate reasonableness of results.

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