Finding Missing Sides Using Perimeter

The video tutorial introduces third graders to the concept of perimeter, presenting it as a puzzle to find unknown lengths. The teacher guides students through various word problems, including a sandbox, a lace decoration, and a rectangular window, using algebraic reasoning to solve for missing side lengths. Students are encouraged to practice these concepts through guided examples and independent exercises, reinforcing their understanding of how to calculate perimeter and apply algebraic thinking to real-world scenarios.

What is the perimeter of a shape?

• The number of sides the shape has

• The total distance around the shape

• The length of the longest side

• The area inside the shape

How can algebra help in finding the unknown side of a polygon?

• By counting the number of sides

• By measuring each side

• By using known side lengths and the perimeter

• By calculating the area

In the sandbox example, what is the length of the missing side if the perimeter is 16 feet?

• 3 feet

• 5 feet

• 2 feet

• 6 feet

In the decoration example, how long should the fourth straw be if the total lace is 22 inches?

• 6 inches

• 4 inches

• 10 inches

• 8 inches

What is the first step in solving for a missing side using perimeter?

• Divide the perimeter by the number of sides

• Multiply the side lengths

• Add the known side lengths

• Subtract the known sides from the perimeter

In the window frame problem, what should be the length of the window if the width is 3 feet and the perimeter is 18 feet?

• 3 feet

• 5 feet

• 6 feet

• 4 feet

For Novak's room, if the perimeter is 52 feet, what is the missing side length?

• 8 feet

• 6 feet

• 10 feet

• 12 feet

In the quadrilateral problem, what is the value of x if the perimeter is 28 centimeters?

• 7 cm

• 5 cm

• 9 cm

• 11 cm