Parts of a circle

Hi Bright Minds, welcome back!!! Colin Powell once said, “A dream doesn’t become reality through magic; it takes determination and hard work.”

Can you believe PEP is over! Now you can relax a bit and breathe a little. Now let’s have fun with Math.

Objective:

Students will identify and describe the parts of a circle:

centre, radius, diameter, circumference, sector

STORY: “THE PARK DESIGN PROJECT”

The Circle Community Park Committee will be making a park for their new community and has hired you and your friends as Junior Designers to help build the new community park. The park includes circular features such as fountains, tracks, and gardens. To ensure this project is done correctly, we will need to ensure we have all its measurements.

1. ENGAGE – PART 1: THE MYSTERY OF THE FOUNTAIN

The park designer shows you a plan for a large circular fountain in the centre of the park.

She says:

“This fountain is perfectly round, but we need to understand its parts so we can design paths, fences, and decorations around it.”

Some workers describe the fountain differently:

One points to the middle.

Another measures across.

Another walks around the edge.

The designer asks:

“Can you identify and name each part of this circle?”

Tasks

A. What shape is the fountain? _________________

B. What part of the circle do you think is most important? Why? ___________________________

C. How would you describe the middle of the circle? ___________________

2. EXPLORE – PART 2: INVESTIGATING THE PARK DESIGN

You are given a drawing of the fountain. Lines are drawn from the middle to the edge, across the circle, and around the outside.

You are told:

Some lines go from the centre to the edge.

Some go all the way across.

Some follow the curved edge.

Investigation Tasks

Using the diagram:

1.A) Which line runs from the centre to the edge? ____________

B) Which line runs across the circle through the centre? ______________

C) Trace around the outside edge. _________________

D) Shade a slice of the circle.

What do you think?

A) What do you notice about the line from the centre to the edge? ___________

B) How is the line across different? _______________

C) What is special about the curved edge? ___________________________

Answer these:

A) “The line from the centre to the edge is called _______________.”

B) “The line across the circle is called __________________.”

3. EXPLAIN – PART 3: THE DESIGN GUIDE

The park designer gives you a guide to help complete your work.

Key Concepts

A circle is a round shape where all points are the same distance from the centre.

Centre

The middle point of the circle

Radius

A line from the centre to the edge

Diameter

A line across the circle through the centre

It is twice the radius

Circumference

The distance around the circle

Sector

A “slice” or part of the circle

4. ELABORATE – PART 4: DESIGNING THE PARK

The Walking Track

The designer wants to build a walking track around the fountain. This will allow persons to run or walk around the fountain.

Tasks

A) Which part of the circle represents the track? ______________

Explain your answer: __________________________________________

The Water Pipe

A pipe runs from the centre of the fountain to the edge. This allows water to be distributed to different parts of the fountain.

Tasks

B) What part of the circle is this? _________________________________

Explain how you know.

The Bridge Across

A bridge is built across the fountain, passing through the centre. This allows persons to look at fishes that may be in the water.

Tasks

C) What part of the circle is this? ___________________________

D) How is it related to the radius? __________________________

The Garden Section

The designer divides part of the fountain area into sections for different water animals.

Tasks

E) What is each section called? ___________________

F) Draw and label one section. ___________________

5. EVALUATE – FINAL DESIGN TASK

You are now responsible for labelling the final design before construction begins.

Tasks

A) On a diagram of a circle:

B) Label the centre.

C) Draw and label a radius.

D) Draw and label a diameter.

E) Label the circumference.

F) Shade and label a sector.

Reflection

1.Which part of the circle was easiest to identify? Why?

2.Which part was most challenging?

3.How are the radius and diameter related?