New
New
Year 5

Calculate missing dimensions in rectangles and compound rectilinear shapes

I can calculate missing dimensions in rectangles and compound rectilinear shapes.

New
New
Year 5

Calculate missing dimensions in rectangles and compound rectilinear shapes

I can calculate missing dimensions in rectangles and compound rectilinear shapes.

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Lesson details

Key learning points

  1. Division is used to calculate a missing dimension when the area and the other dimension are known.
  2. Inverse operations are used to calculate missing dimensions when areas are known.
  3. Compare different methods to decompose shapes and decide which is the most efficient.

Common misconception

Applying known facts and strategies to solve problems involving division. Being able to break down a problem into steps when it comes to compound shapes.

Provide opportunities to discuss approaches and highlight the efficient strategies and approaches. Acknowledge that there is more than one way to solve a problem whilst focusing on efficient and effective strategies.

Keywords

  • Compound - A compound shape is made up of two or more shapes.

  • Dimension - A dimension is a measurement of length in one direction. Width and height are examples of the dimensions of 2D shapes.

Licence

This content is © Oak National Academy Limited (2024), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).

Video

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6 Questions

Q1.
x 7 = 56
Correct Answer: 8, eight
Q2.
96 = x 8
Correct Answer: 12, twelve
Q3.
Which of these compound rectilinear shapes have a total area of 60 m²?
An image in a quiz
a
Correct answer: b
Q4.
Which calculation would you use to calculate the area with the information you have been given?
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72 cm² − 10 cm² = 62 cm²
Correct answer: 42 cm² + 20 cm² = 62cm²
48 cm² + 14 cm² = 62 cm²
Q5.
Jun worked out the area of a compound shape. Which of these shapes was he calculating the area of?
An image in a quiz
An image in a quiz
Correct Answer: An image in a quiz
An image in a quiz
An image in a quiz
Q6.
What is the area of the grey path around the pond?
An image in a quiz
Correct Answer: 46m², 46 m², 46m2, 46 m2

6 Questions

Q1.
What is the missing dimension
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Correct Answer: 4 cm, 4cm, 4, 4CM, 4 CM
Q2.
What is the missing dimension?
An image in a quiz
Correct Answer: 7 cm, 7cm, 7, 7 CM, 7CM
Q3.
What is the missing dimension?
An image in a quiz
Correct Answer: 23 cm, 23cm, 23, 23 CM, 23CM
Q4.
The area of this compound shape is 116 cm². What is the missing dimension?
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6 cm
Correct answer: 7 cm
8 cm
5 cm
Q5.
Here is a shape made from three identical rectangles. The area of the shape is 180 cm². What are the missing dimensions?
An image in a quiz
12 cm and 6 cm
11 cm and 5 cm
Correct answer: 12 cm and 5 cm
11 cm and 6 cm
Q6.
The larger blue rectangles are double the area of the smaller red rectangles. Calculate the area of a small red rectangle.
An image in a quiz
Correct Answer: 50 cm², 50cm², 50, 50cm2, 50 cm2