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The video tutorial introduces third graders to the concept of perimeter, explaining it as the measurement around the outside of an object. It demonstrates how to find the length of a missing side when the perimeter is known, using examples of a triangle, a quadrilateral, and a complex shape. The tutorial emphasizes addition and subtraction methods to solve for the missing side and encourages students to practice these techniques.

What is the perimeter?

• The measurement around the outside of an object

• The area inside an object

• The length of one side of an object

• The volume of an object

If a triangle has two sides of 7 units each and a perimeter of 19 units, how long is the missing side?

• 12 units

• 7 units

• 5 units

• 19 units

How can you find the length of a missing side when you know the perimeter?

• Divide the perimeter by the number of sides

• Multiply the known sides

• Subtract the lengths of the known sides from each other

• Add the lengths of the known sides and subtract from the perimeter

Why is understanding perimeter important?

• To calculate the area of shapes

• To measure the distance around a shape

• To determine the volume of a shape

• To find the height of a shape

What does 'units' refer to in the context of perimeter?

• Square measurements

• Only centimeters

• Any standard measure of length

• Only meters

In a shape with a perimeter of 20 units and three known sides of 5, 3, and 5 units, what is the length of the missing side?

• 5 units

• 3 units

• 7 units

• 10 units

What is the first step in finding a missing side if you know the perimeter?

• Divide the perimeter by the number of sides

• Add all the known sides together

• Subtract the largest side from the perimeter

• Guess the length of the missing side

If the perimeter of a shape is 48 centimeters and the known sides are 3, 15, 3, and 15 centimeters, what is the length of the missing side?

• 48 centimeters

• 12 centimeters

• 24 centimeters

• 15 centimeters

What mathematical operation is primarily used to find the missing side when the perimeter is known?

• Division

• Subtraction

• Addition

• Multiplication

When given the perimeter and lengths of some sides, what is a strategy to find the missing length?

• Estimate the missing length

• Add the lengths of all known sides and subtract from the perimeter

• Multiply all known lengths and compare to the perimeter

• Divide the perimeter by the number of known sides