Numeracy Skills
in D&T
CALCULATING AREA
2D (Two-dimensional) Calculations
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Numeracy Skills
What is an area?
Area is a 2D property of shapesWhat is an area?
It is one of the most important and useful calculations that a person should know. It is used in all sorts of everyday scenarios in real life. Use the following videos to help you understand the following topics.
Consider a person hanging wallpaper in their lounge.
a) How do they know how many rolls to buy?
b) Can they afford to buy the style they like?
Wallpaper is sold in rolls of different widths and lengths.
To calculate how many rolls, you need to know the total area of the space you are covering and divide it by the total usable area that a single roll would cover.
Area Explained
Circles Area/Circumference Explained
Activity 2.1. Area of simple squares & rectangles
Activity 2.1. Area of simple squares & rectangles
Remember to use brackets correctly AND enter your units in the method.
Calculating the area of a triangle
Calculating the area of a triangle
Consider the following animation. It will help you remember the formula for the area of a triangle.
Activity 2.2. Area of right-angled and isosceles triangles
Activity 2.2. Area of right-angled and isosceles triangles
Remember to use brackets correctly AND enter your units in the method.
Pay attention closely as sometimes you will be shown isosceles triangles.
In these cases, make sure that you use the triangle height - not the equal side length to calculate the area.
Activity 2.3. Area of compound rectangles
Activity 2.3. Area of compound rectangles
Remember to use brackets correctly AND enter your units in the method.
Remember that compound areas are treated as three step calculations:
Calculate the area of 'shape-section 1'.
Calculate the area of 'shape-section 2'
Add the two together to combine them into a single shape area.
Calculating the area of circles
Calculating the area of circles
Click here to refresh your memory of the value pi, a critical property of circles which is needed to calculate the area of one.
Pay attention to the questions. You will not always be given the same value. You will need to be alert for changing values between radius, r and diameter, ø. Remember to use brackets correctly. Remember to use brackets correctly AND enter your units in the method.
Activity 2.4. Area of circles
Activity 2.4. Area of circles
Using your knowledge of Pi and circles, practice calculating their area below. When you are ready, carry out the test.
Extensions 'Area & Volume' Assessments
Extensions 'Area & Volume' Assessments
These are the assessments you will be given in-class to determine whether you are developing, meeting or exceeding your numeracy target skills.
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