Exploring Perimeter of Polygons with Practical Examples
Join Margo in solving real-world problems involving perimeter of polygons. Learn how to find the perimeter of shapes like rectangles and squares through engaging activities and investigate the concept of perimeter in a hands-on manner. Discover essential questions and practical applications of measuring perimeter in everyday scenarios.
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Lesson 25 Perimeter of Polygons
[OBJECTIVE] The student will solve problems involving perimeter of polygons.
[MYSKILLS] Multiplication Facts (0 9)
[ESSENTIALQUESTIONS] 1. How can the perimeter of a square be found using a formula? 2. How can the perimeter of a rectangle be found using a formula? 3. How can a missing side of a polygon be determined if the perimeter of the polygon is known?
SOLVE Margo is helping her dad build a pen in the backyard for her new puppy. She got the puppy for her birthday. The pen is in the shape of a rectangle. The length of the pen is 8 feet, and the width of the pen is 6 feet. What is the perimeter of the pen? S Study the Problem Underline the question. This problem is asking me to find the pen s perimeter.
[Cooperative Pairs] Partner A Partner B
Investigate Perimeter of Polygons Trace your finger around the edge of your desktop. This is the perimeter of the desk. What do you think perimeter means? It is the distance around a figure. When might it be useful to know how to measure the perimeter of any surface? It may be useful when putting up a border on the bulletin board, or when putting up a fence in a yard.
Investigate Perimeter of Polygons Using toothpicks, create a square! What do you notice about the square? All of the sides are equal, or the same size. How many sides does the square have? 4 sides
Investigate Perimeter of Polygons Using toothpicks, create a square! How many toothpicks were used to create the square? 4 toothpicks
Investigate Perimeter of Polygons Using toothpicks, create a square! If each of the toothpicks is considered one unit of measurement, what is the perimeter or distance around the edge of the square? 4 units
Investigate Perimeter of Polygons Let s transfer the toothpick square to the grid paper and shade. P = 4 units What is the perimeter of the square? 4 units
Investigate Perimeter of Polygons Add another square by adding 3 more toothpicks. How many units are on the top of the rectangle? 2 units
Investigate Perimeter of Polygons Add another square by adding 3 more toothpicks. How many units are on the bottom of the rectangle? 2 units
Investigate Perimeter of Polygons Add another square by adding 3 more toothpicks. How many units are on the left side of the rectangle? 1 unit
Investigate Perimeter of Polygons Add another square by adding 3 more toothpicks. How many units are on the right side of the rectangle? 1 unit
Investigate Perimeter of Polygons Add another square by adding 3 more toothpicks. What is the perimeter of the rectangle? 6 units
Investigate Perimeter of Polygons Let s transfer the toothpick rectangle to the grid paper and shade. P = 4 units P = 6 units How many squares are in the toothpick rectangle? 2 squares How many units of perimeter are shown for the shaded rectangle? 6 units
Investigate Perimeter of Polygons What is the shape? Side 1 Side 2 Side 3 Side 4 2 units Square Perimeter 1 2 If Side 1 is the top of the square, identify the number of units for this side. 2 units
Investigate Perimeter of Polygons What is the shape? Side 1 Side 2 Side 3 Side 4 Square Perimeter 2 2 units units If Side 2 is the right side of the square, identify the number of units for this side. 2 units 1 2
Investigate Perimeter of Polygons What is the shape? Side 1 Side 2 Side 3 Side 4 Square Perimeter 2 2 2 units units units If Side 3 is the bottom of the square, identify the number of units for this side. 2 units 1 2
Investigate Perimeter of Polygons What is the shape? Side 1 Side 2 Side 3 Side 4 Square Perimeter 2 2 2 2 P = 2+2+2+2 = 8 units units units units units If Side 4 is the left side of the square, identify the number of units for this side. 2 units 1 2
Investigate Perimeter of Polygons Perimeter Side 1 Side 2 Side 3 Side 4 4 ft How is this problem different from the first problem?There are no units showing inside of the square, but the dimensions are given. 4 ft 4 ft 4 ft
Investigate Perimeter of Polygons Perimeter Side 1 Side 2 Side 3 Side 4 4 ft Identify the units for this square. Feet 4 ft 4 ft Describe the sides of the square. They are all equal. 4 ft
Investigate Perimeter of Polygons Perimeter Side 1 Side 2 Side 3 Side 4 P = 4+4+4+4 = 16 feet 4 ft 4 ft 4 ft 4 ft 4 ft Identify the measure of each side to find the perimeter of the square. 4 ft 4 ft 4 ft
Investigate Perimeter of Polygons The shape is a: Side 1 Side 2 Side 3 Side 4 Square Perimeter P = 6+6+6+6 = 24 m 6 m 6 m 6 m 6 m In this problem, we don t have a picture, but we have dimensions. How can we find the perimeter? Add all of the dimensions given to find the perimeter of this square.
Missing Sides Perimeter Side 1 Side 2 Side 3 P = 12 m 3 m 5 m How is the problem different from the other problems? The perimeter is given, but we are missing a side. 5 m 3 m ___ m
Missing Sides Perimeter Side 1 Side 2 Side 3 P = 12 m 3 m 5 m Identify the number of meters for Side 1. 3 meters Identify the number of meters for Side 2. 5 meters 5 m 3 m ___ m
Missing Sides Perimeter Side 1 Side 2 Side 3 P = 12 m 3 m 5 m What is the sum of the known sides? 3 meters + 5 meters = 8 meters How can we find the missing side? Add the two sides, then subtract from the perimeter. 5 m 3 m ___ m
Missing Sides Perimeter Side 1 Side 2 Side 3 P = 12 m 3 m 5 m 4 m 12 8 = 4 meters Side 3 = 4 meters P = 3 + 5 + 4 = 12 meters 5 m 3 m ___ m
Rectangles and Square Using Formulas Perimeter Length Width 4 units What does length mean? how long an object is Picture What is the length of the rectangle? 4 units
Rectangles and Square Using Formulas Perimeter Length Width 4 units 1 unit What does width mean? how wide an object is Picture What is the width of the rectangle? 1 unit
Rectangles and Square Using Formulas Perimeter Length Width 4 units 1 unit How did you find the perimeter of the rectangles in the last activity? Picture We added each side together to find the total, or sum.
Rectangles and Square Using Formulas Perimeter Length Width 4 units 1 unit What is the total length of the top and bottom of the rectangle? 8 units Picture How did you determine the total length? Multiply the top or bottom length by 2 or double one length.
Rectangles and Square Using Formulas Perimeter Length Width 4 units 1 unit What is the total width of the two sides of the rectangle? 2 units Picture How did you determine the total width? Multiply one side length by 2, or double one width.
Rectangles and Square Using Formulas Perimeter Length Width 4 units 1 unit Can you think of a way to find the perimeter of the rectangle using what you know about the length and the width? Multiply the length by 2. Multiply the width by 2. Add the products together. Picture
Rectangles and Square Using Formulas Perimeter Length Width 4 units 1 unit What letters might represent the perimeter, length and width? P for perimeter l for length w for width Picture
Rectangles and Square Using Formulas Perimeter P = 2l + 2w P = 2(4)+2(1) Length Width 4 units 1 unit Can you think of a way to describe finding the perimeter using the letters in a formula? P = 2l + 2w Picture
Rectangles and Square Using Formulas Perimeter P = 2l + 2w P = 2(4)+2(1) Length Width 4 units 1 unit P = 2(4) + 2(1) P = 8 + 2 P = 10 units Picture
Rectangles and Square Using Formulas Perimeter Length Width How did you find the perimeter of the rectangles in the previous activity? Picture We added each side together to find the total, or sum.
Rectangles and Square Using Formulas Perimeter Length Width 3 units 3 units How can we find the perimeter of the square using only the length of one side? Picture Multiply one side by 4, because each of the 4 sides measures 3 units.
Rectangles and Square Using Formulas Perimeter Length Width 3 units 3 units What letters might represent the perimeter and side. Picture P for perimeter s for side
Rectangles and Square Using Formulas Perimeter P=4s P=4(3)=12 units Length Width 3 units 3 units Establish a way to describe finding the perimeter using one side length, beginning with P =. P = 4s Picture
Rectangles and Square Using Formulas Perimeter Length Width Even though we only know one side of the figure, what do we know about a square? The square has four equal sides and four equal angles. Picture 5 in.
Rectangles and Square Using Formulas Perimeter Length Width 5 inches 5 inches If the length of the square is 5 inches, what is the width? Picture 5 in. 5 inches
Rectangles and Square Using Formulas Perimeter P = 4s P = 4(5) P = 20in. Length Width 5 inches 5 inches What formula will we use to find the perimeter of the square? P = 4s P = 4(5) P = 20 inches Picture 5 in.
Rectangles and Square Using Formulas Perimeter P = 4s P = 4(5) P = 20in. Length Width 5 inches 5 inches Could we use the formulas for finding the perimeter of a triangle or trapezoid? No, because a triangle has 3 sides, and they are not always equal. A trapezoid has sides that are different lengths and widths. Picture 5 in.
