Circumference is the distance all around a circle or ball.

In this activity, students are introduced to circumference and measurement, using string, balls, and Unifix® cubes to explore and compare the sizes of different balls and spheres.

Round the Circle: printable guide.

These activities are part of Science World’s Big Science For Little Hands program. They were developed and tested with preschool and kindergarten educators.

### Objectives

• Understand and measure circumference of a sphere.

### Materials

• Per Student:
lengths of string, cut to fit around at least the largest ball

• Per Group:
a variety of different-sized balls and/or spheres (e.g. tennis balls, basketballs, golf balls, fruit, etc)
Unifix® cubes  or Duplo®/Lego® (optional – for further measurement)

### Key Questions

• What ball has the smallest circumference? Largest? (How many cubes long are they?)
• What else can we use to measure circumference?Can you put the balls in order, from smallest to largest circumference?

### What To Do

2. Make a mark with a felt pen where the end of your string touches the rest of the string.
3. Stretch out your string and see where the felt mark is. This is the circumference.
4. If available, line up interlocking Unifix® cubes all along the circumference-length of string. How many cubes ‘long’ is it?

### Extensions

• Try measuring the circumference of other spherical objects. If it's around Halloween, pumpkins are a great option.
• Go on a neighbourhood exploration for circles and spheres, or have students bring some items from home (e.g. toilet paper rolls, a can, etc) to measure their circumferences.
• After some practice, try predicting circumference. Collect other round objects and make a 'prediction mark' on your string with a different colour felt pen, then measure it and mark the actual circumference. Try a few times to see see if you improve.

Survivors

Artist: Jeff Kulak

Jeff is a senior graphic designer at Science World. His illustration work has been published in the Walrus, The National Post, Reader’s Digest and Chickadee Magazine. He loves to make music, ride bikes, and spend time in the forest.

Egg BB

Artist: Jeff Kulak

Jeff is a senior graphic designer at Science World. His illustration work has been published in the Walrus, The National Post, Reader’s Digest and Chickadee Magazine. He loves to make music, ride bikes, and spend time in the forest.

Comet Crisp

Artist: Jeff Kulak

Jeff is a senior graphic designer at Science World. His illustration work has been published in the Walrus, The National Post, Reader’s Digest and Chickadee Magazine. He loves to make music, ride bikes, and spend time in the forest.

T-Rex and Baby

Artist: Michelle Yong

Michelle is a designer with a focus on creating joyful digital experiences! She enjoys exploring the potential forms that an idea can express itself in and helping then take shape.

Buddy the T-Rex

Artist: Michelle Yong

Michelle is a designer with a focus on creating joyful digital experiences! She enjoys exploring the potential forms that an idea can express itself in and helping then take shape.

Geodessy

Artist: Michelle Yong

Michelle is a designer with a focus on creating joyful digital experiences! She enjoys exploring the potential forms that an idea can express itself in and helping then take shape.

Science Buddies

Artist: Ty Dale

From Canada, Ty was born in Vancouver, British Columbia in 1993. From his chaotic workspace he draws in several different illustrative styles with thick outlines, bold colours and quirky-child like drawings. Ty distils the world around him into its basic geometry, prompting us to look at the mundane in a different way.

Western Dinosaur

Artist: Ty Dale

From Canada, Ty was born in Vancouver, British Columbia in 1993. From his chaotic workspace he draws in several different illustrative styles with thick outlines, bold colours and quirky-child like drawings. Ty distils the world around him into its basic geometry, prompting us to look at the mundane in a different way.