Transcript Block 19 elementary - MATH GR 3-5

Perimeter & Area
Measurement
Why do we measure objects?
Name a household object that
can be measured?
Standard Measurement
Customary VS Metric
inches, feet, yards
VS
centimeters and meters
NON-Standard Measurement
Video example
of
non-standard
measurement
Perimeter
The perimeter is the
distance around the outer
limits of any two dimensional
object.
Perimeter
Look at the sides of an object.
They come together to make a shape.
Perimeter
If we want to know the distance around
the shape, we measure the sides and
4”
add the lengths.
2”
5” + 3” + 3” + 1” + 2” + 4”
or
18”
1”
5”
3”
3”
No matter how odd the shape is, you
just add the sides together.
Area
The area of a figure measures the size
of the region enclosed by the figure. This
is usually expressed in terms of some
square unit.
Area
The area in INSIDE the figure and is expressed as square
meters, square centimeters, square inches, or square feet.
Difference
What is the difference between
AREA and PERIMETER?
Why do people confuse AREA
and PERIMETER?
Misconceptions
After giving definitions for perimeter and
area, Mrs. Gonzalez gave her class the
following problem.
Find the area and perimeter for the
square that has a side of 4 inches.
Misconceptions
Gianni, a student in the class drew the
square on his paper:
4”
4”
4”
4”
Gianni indicated each side of the square
was 4”.
Misconceptions
Gianni wrote:
Perimeter is 16
Area is 16
Is Gianni correct?
Did Mrs. Gonzalez do anything wrong?
Misconceptions
What would you say to help
Gianni?
Misconceptions
Gianni and his best friend have both
worked on this problem:
Given a square with side 3,
find the area.
3”
3”
Misconceptions
3”
3”
Gianni said the area is 9 square inches
and his friend Jen said it is 12 square
inches.
Who is right, Jen or Gianni? PROVE IT!
Misconceptions
1
3” 4
7
2
5
8
3”
How do you prove it?
3
6
9
Misconceptions
Next, Gianni & Jen work on this
problem:
Find the area for this
rectangle.
4”
7”
Misconceptions
4”
7”
Gianni said the area is 28 square inches
and Jen said it is 22 square inches.
Who is right, Jen or Gianni?
Misconceptions
4”
7”
How did Gianni get his answer?
How did Jen get her answer?
Misconceptions
4”
7”
Who is right?
How do you prove it?
Misconceptions
What does this mean?
36 square
units
Misconceptions
Gianni looked at this problem and wrote
9
9
36 square
9
units
9 inches
9
What did he do? Is he correct?
Misconceptions
Jen looked at this problem and wrote
36 square
units
1296 inches
What did she do? Is she correct?
Misconceptions
Bart laughed at both Jen and Gianni and
wrote:
36 square
units
36 ÷ 6 = 6
What did he do? Is he correct?
Misconceptions
Christy did the following:
36 square
units
6 inches
What did she do? Is she correct?
Misconceptions
If this represented a square pizza, what
would be the length of the cheese
stuffed crust?
36 square
units
Vocabulary Foldable
• Foldable
– Two 8.5 x 11 sheets of paper
– Fold (hamburger style) both sheets
– Put one folded sheet on top of other (with about
¼” of bottom sheet showing
– Use pencil and place a mark approximately 1”
from each end
Vocabulary Foldable
• Make sure you mare each sheet in same place
• Cut sheet 1 along seem TO the line you make from
each end
• Cut sheet 2 between the lines
Vocabulary Foldable
• Roll sheet 1 line a hotdog
• Place in between sheet 2
• Open so slits go inside ends of center cut sheet
You now have an 4 page (8 sided book)!
Vocabulary
Length
Width
Height
Base
Perimeter
Area
Vocabulary
Polygon
Quadrilateral
Rectangle
Square
Parallelogram
Rhombus
Review
What have you learned?
Write 3 facts.