Perimeter 3rd Grade

Perimeter​

I can use addition and multiplication to find the perimeter of plane figures.

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When do we need to find the perimeter?

• Solving how much fence we need to go around a yard

• Solving how many tiles are needed to go around a swimming pool

• Solving how long a race track is around a field

• Solving how long the boundaries are around a soccer field

How do we find the perimeter?

We find perimeter by counting the units around the shape, or adding the length of all of the sides together.

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Perimeter=L+L+W+W​

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Multiple Choice

What is the PERIMETER of this shape?

• 20 inches

• 21 inches

• 14 inches

• 6 inches

Multiple Choice

What is the perimeter of this shape?

• 4 units

• 10 units

• 20 units

• 6 units

Multiple Choice

What is the perimeter?

• 21 ft

• 10 ft

• 20 feet

• 20 square feet

Multiple Choice

what is the perimeter of the triangle?

• 14 m

• 15 m

• 16 m

• 20 m

Multiple Choice

What is the perimeter of the rectangle? (Hint: top matches the bottom, left matches the right!)

• 48 feet

• 27 feet

• 28 feet

• 30 feet

Multiple Choice

The perimeter of the shape is 20 units. What is the length of the missing side?

• 4 units

• 6units

• 7 units

• 8units

Multiple Choice

What is the perimeter of the fence?

• 25

• 30

• 35

• 40

​Some shapes are IRREGULAR!

Just add the sides

Multiple Choice

What is the perimeter of this shape?

• 24cm

• 8cm

• 35cm

• 17cm

Fill in the Blanks

Multiple Choice

Farmer Bob needs to build a fence for his chickens. The area he wants to build a fence around is 40 feet long and 20 feet wide. How many feet of fence does he need to buy?

• 800 feet

• 120 feet

• 60 feet

Poll

How well do you understand perimeter?

• I could teach it!

• It's pretty easy!

• I almost got it!