Lesson 4 - Area of a Circle
The objective of this fourth and final lesson is to determine how to calculate the area of a circle. We shall recap on what we have learned in the last lesson as a class and then work in pairs to complete the lesson activity before undertaking the quiz, assessments and end of topic test individually.
Revision
We hope you enjoyed Lesson 3 and now know lots of facts about Pi and decimal places. Before we start the topic for today let's quickly recap on decimal places.
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What's the Formula?
You can find the area of a circle by using the formula Area = π x radius²
The formula to calculate the area of a circle is A = πr² but this is hard to visualise and hard to prove. So we cut the circle into wedges and place half of the wedges face-up and half face-down.
Use your mouse to change the radius of the circle by moving the black point with your mouse along the black slider. The circles radius is the black number.
Use your mouse to change the radius of the circle by moving the black point with your mouse along the black slider. The circles radius is the black number.
Use your mouse to change the number of segments the circle is made up of by moving the pink point with your mouse along the pink slider.
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As the number of wedges increases, the black vertical line, the radius, and the hanging-out blue pieces start to fit inside the red rectangle.
Isn't that cool? Showing this mathematically is called calculus!
Isn't that cool? Showing this mathematically is called calculus!
Quiz Time!
Song time!In Lesson 3 we looked at memorising and how a poem can help us remember facts like the value of Pi. Listen to the song and hopefully it will help you remember the circle terms and formulae.
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Practise Time!Lets put this new knowledge to the test! Please log into your www.sumdog.com account via the button below and complete the allocated tasks.
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Test Time!
You have completed all four lessons on our journey of discovery so it is time to put your skills and knowledge to the test by completing an end of topic test. Do you think you are ready? You know you are, so click the button and go for it!
Homework and Early Finishers
If you haven't finished the allocated Sumdog activity and assessment during the lesson you will have to complete them both for homework. You are also required to download the worksheet and complete it before the next lesson.
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