This audio presentation discusses perimeter and area. It defines perimeter as the distance around an object and area as the number of square units needed to cover a surface. It provides examples of calculating perimeter by adding all sides of a shape and calculating area by multiplying length by width. Real-world examples are given of using perimeter to find fencing needs or sidewalk distance and using area to find carpet, concrete or paint requirements. Students are instructed to take notes on the definitions and formulas, then measure objects to practice calculating perimeter and area.
1. Audio for Perimeter and Area PowerPoint
Kimberly Lantz DeHaven
Begin- Slide 1- Today we are going to learn how to find the perimeter and
area of an object or shape and learn how we might use this in our everyday
lives.
Slide 2- Perimeter is defined as the distance around an object or figure.
The pictures show some examples of objects that we can use when we want
to find perimeter. The black line around the blue rectangle would represent
the perimeter. The wood border around the planter represents its
perimeter. On the picture of the house, the fence represents the perimeter
of the yard.
Let’s take a moment to write the definition of perimeter in our notes.
Slide 3- To find perimeter, we use addition. We need to add all sides of the
object or shape. The rectangle example to the left has already been
measured for us. We would need to add the measures of all 4 sides. So, we
would add 6 + 6 + 3+ 3= 18. The rectangle is measure in feet, so our answer
would be 18 feet.
Let’s write the formula for finding perimeter in our notes. We need to write
side + side + side + side =. We would need to add more “sides” for an object
that had more than 4 sides. Draw an example of perimeter in your notes
using different measurements than the example.
Slide 4- Here are some examples of ways we could use perimeter in real life.
We would need to know the perimeter of our yard in order to buy enough
fencing to go around it. We could use the formula for perimeter to find the
distance of sidewalk around a city block. You would also need to use the
concept of perimeter to know how much fabric you need to add trim to your
quilt.
Let’s brainstorm some other real life situations where you think we may need
to use perimeter. Take a few minutes to think about it and write your ideas
in the margin of your paper. We will then discuss and list some of your ideas
on the board.
Slide 5- Now let’s talk about the area of an object or shape. Area is defined
as the number of square units needed to cover a surface or figure. Look at
2. the pictures. In the top picture of the courtyard, focus on the grassy
section. You would need to know the area of that section to purchase grass
seed or sod (rolls of grass) to cover it. On the left you see a woman rolling
out carpet. This is the most common instance we may think of when talking
about area. You always need to know the area of a room to purchase the
right amount of carpet. In the other photo you see a girl painting a wall.
The area of each wall you intend to paint would be needed to make sure you
have enough paint to cover it.
Let’s take a moment to write the definition of area in our notes.
Slide 6- To find area we multiply the length times the width of the object or
surface. This example is measured in units. We would multiply the length of
8 by the width of 8. 8 x 8 = 64, so the area of this surface is 64 square
units. We always state area in square units (or inches, feet, yards, etc…
depending on what we are using to measure the length and width. If this had
been measured in inches, we would have stated the area as 64 square inches.
Let’s write the formula for area in our notes now. We need to write length
times width equals. We also need to make a note to remind us to state the
answer in square units. Draw an example of area in your notes using
different measures than our example.
Slide 7- Here we have some examples of how we use area in real life
situations. In the first picture we have another example of carpeting a
room. A carpenter would need to use the formula for area to make sure
they have enough carpet for your room. In the second picture you see a
concrete driveway. You would need to calculate the area of the driveway to
know how much concrete to purchase for your entire driveway. And then
again in the third picture we have the girl painting. She would calculate the
area of the wall or walls that she wanted to paint so she could go and
purchase her paint.
Let’s brainstorm some other instances where we may need to use area in our
lives. Take a few minutes to think, write your ideas in the margin of your
notes, and then we will share our examples and discuss them. We can then
list them on the board.
3. Now that we have taken our notes and discussed perimeter and area, let’s
take our rulers and go around the room to measure at least 4 objects. We
will measure the objects to the nearest inch. Determine with your partner
whether you will need to use perimeter or area for the object. Once you
have measured your objects, we will meet back at the table to discuss our
measures and calculations. Make sure each person has a chance to measure
and calculate.