1.1 Calculate perimeter and area of triangles & rectangles

• Mathematics
• Lower Secondary (Key Stage 3)

Tell me two truths and a lie about yourself!

Calculate perimeter and area of triangles & rectangles

What is a triangle?

Triangle: a definition

A triangle is a closed, 2-dimensional shape with 3 sides, 3 angles, and 3 vertices. A triangle is also a polygon.

What is a rectangle?

Rectangle: a definition

A rectangle is a 2D shape that has 4 sides, 4 corners, and 4 right angles. Opposite sides of a rectangle shape are the same length, with one pair being longer than the other pair. If all the sides of a rectangle were the same size, it would be known as a square.

What is the perimeter of a shape?

Perimeter: a definition

The perimeter is the distance around the edge of a shape. 

What is the area of a shape?

Area: a definition

The total space taken up by a flat (2-D) surface or shape of an object. 

Perimeter: Introduction

Task

You will need:

• Clip board
• Pencil
• Squared paper
• a device with a camera
• 30cm Ruler, metre ruler, tape measure/trundle wheel
• A maths partner

Task

Challenge:

• find 5 triangles
• find 5 rectangles
• sketch the triangles and rectangles
• label the perimeter of the sketches with your measurements
• find small, medium and large triangles and rectangles
• use the ruler, metre stick, trundle wheel and tape measure
• photograph each triangle and rectangle

Triangle and rectangle scavenger hunt

See you in 15 minutes!

What was the largest perimeter of a rectangle that you found?

What was the smallest perimeter of a triangle you found?

Drag

Use this to drag the screen around

Zoom

Use this to zoom in and out in order to see more/less detail

Connection line

Use this to connect the question with your answer - use a sticky note to add your answer. Don't forget to add your name to the sticky note!

Questions

Choose a question to answer

Miro Board

Success!

Success will lok like this!

Miro Board Activity

https://miro.com/welcomeonboard/Q3loQUpJbkNIRFlGOWF0QXZYSTdoaEpQWmh6eGdLYldkZ0g1WVh4dUdZNEUyZWxTdE5ZTTFtV0pMcjBmU3l5enwzNDU4NzY0NTUzNjIyODU4ODU4fDI=?share_link_id=64530589502

Activities

Perimeter

https://www.khanacademy.org/math/geometry-home/geometry-area-perimeter/geometry-perimeter/e/perimeter-2

Perimeter

https://www.khanacademy.org/math/geometry-home/geometry-area-perimeter/geometry-perimeter/e/find-a-missing-side-length-when-given-perimeter

Perimeter

https://nrich.maths.org/content/id/11119/Perimeter%20Challenge.pdf

Perimeter and Area

Finding the area of your rectangles!

What is the area of your largest rectangle? Show your working out!

Activities

Area of rectangles

https://www.khanacademy.org/math/cc-third-grade-math/imp-geometry/imp-multiply-to-find-area/e/area-of-squares-and-rectangles

Find a missing side

https://www.khanacademy.org/math/cc-third-grade-math/imp-geometry/imp-multiply-to-find-area/e/find-a-missing-side-length-when-given-area-of-a-rectangle

Comparing areas

https://www.khanacademy.org/math/cc-third-grade-math/imp-geometry/imp-multiply-to-find-area/e/comparing-areas-by-multiplying

Area of a triangle

What is the area of your smallest triangle? Show your working out.

Activities

Area of right-angled triangles:

https://www.khanacademy.org/math/cc-sixth-grade-math/x0267d782:cc-6th-plane-figures/cc-6th-area-triangle/e/area-of-right-triangles

Area of triangles:

https://www.khanacademy.org/math/cc-sixth-grade-math/x0267d782:cc-6th-plane-figures/cc-6th-area-triangle/e/area_of_triangles_1

Finding the length of a triangle side when given the area:

https://www.khanacademy.org/math/cc-sixth-grade-math/x0267d782:cc-6th-plane-figures/cc-6th-area-triangle/e/find-length-when-given-area-of-a-triangle

Miro Board

https://miro.com/welcomeonboard/dDc1YnY1SzVPMmlhS1BKWVloUmhrMXFma0tRcDZvdlBRS0hsM0tGSFRQMWY0cWtyVmR0dDVPMEFnZmhEbThHSHwzNDU4NzY0NTUzNjIyODU4ODU4fDI=?share_link_id=803570527619

Miro Board

Non-right angled triangles

https://miro.com/welcomeonboard/NGFNUERJSTNTUzBsM1ZBVk12VW9WUHMxUWk2ZTI3am5FSVdRUDk4c0Q4dUhlTDdkS0JLNTd6c1IycVlxM1NncXwzNDU4NzY0NTUzNjIyODU4ODU4fDI=?share_link_id=247953557475

Need help? 

Explain how you find the area of a rectangle using only words.

Explain how you find the area of a triangle using only words

I don't fully understand this yet...

I feel very confident about...