Perimeter
1) Purpose
a) To introduce the concept of perimeter
2) Vocabulary and Key Terms
a) Perimeter: the distance around a shape.
3) Skills
a) Measure objects with a ruler to the nearest inch and foot.
b) Add side lengths in inches and feet to find perimeter.
4) Objectives
a) As a result of this lesson, students will be able to understand the concept
of perimeter
b) As a result of this lesson, students will be able to apply their skills of
measuring the length and width of an object in inches and feet to
calculating its perimeter
5) New York State Learning Standards
a) Measurement
i) Units of Measurement
(1) 3.M.1. Select tools and unit (customary) appropriate for the
length measured
(2) 3.M.2. Use a ruler/yardstick to measure to the nearest
standard unit (whole and half inch, whole foot, whole yard).
6) Pre-Assessment
a) In a prior lesson, students learned and applied the skills of measuring the
length and width of the rug, and other classroom objects. They were also
able to calculate feet to inches and inches to feet.
b) Students will use these skills to find perimeter.
7) Lesson Presentation
a) Set-Induction
i) I will remind the students that the day before they measured the
length and width of the rug and other objects. I will ask them why we
would bother measuring the length and width things.
(1) Examples should include build a fence, put a rug down, etc.
b) Procedure
i) I will explain that if we wanted to build a fence around something,
we would have to know the distance around the object. This is called
perimeter. Write on board in English, Spanish (perímetro), and French
(périmètre). The perimeter is the measure of the distance around an
object.
(1) I will show them a square made out of straws. (Tape to white
board). I will explain that to find the perimeter, or the
distance around the straws, I need I need to measure all four
sides. I will measure the sides with a ruler. Each side will be
three inches. (Write 3 inches above each side) I will add 3
inches. (Write 3 inches above each side) I will add 3 inches
four times to get 12 inches as the perimeter. (show on white
board) I will ask the students long they think the straw would
be if we measured it in a straight line. I will then disconnect
the square at one corner and measure the length to
demonstrate it is the same.
(2) I will ask them what we would need to do if we decided to
build a fence around the rug.
(a) Measure all four sides and add the distances.
(3) I will explain that we can use the measurements from the day
before. I will draw a picture of the rug on the white board. I
will label one length and one width and ask if I need to
measure the other length and width. I will explain that it is the
same since it is a rectangle so we do not have to.
(4) I will have the students add the four distances to get the
perimeter.
(5) If students are confused I will do another example.
ii) I will explain like the day before, they will work with their partners to
find the perimeter of three different objects, an index card, the table
top, and the white board. They will record their data onto a teacher-
made worksheet.
(1) I will remind them to measure heel to toe
(2) I will remind them to use the correct units
(3) I will remind them that they will measure to the nearest foot
and inch.
(4) I will remind them that there are several tables, and not to all
measure the same one.
iii) If some pairs finish long before others, they will begin to work on
their math journal page.
c) Closure
i) After they have obtained their three measurements we will share our
results.
8) Materials and Resources
a) Straws and tape
b) 7 rulers
c) Index cards
d) Table tops
e) White board
f) Work sheet
9) Follow-Up Activity
a) Students will receive a worksheet where they have to calculate the
perimeters of various shapes.
10) Evaluation/Assessment
a) Students will be informally evaluated on:
i) Participation during direct instruction on the rug
ii) Ability to follow directions
iii) Ability to use the rulers correctly
iv) Ability to work in pairs
v) Information completed on the worksheet
11) Differentiated
a) ESL
i) There will be many visuals used, including tracing the rectangle to
show perimeter, the word perimeter in Spanish and French, and the
demonstration with the straw square. This is so students, who may
not understand perimeter verbally, can see it visually and
kinesthetically. The Spanish speaking student also has a bilingual
aid to assist her throughout the lesson.
b) One student will receive a therapeutic ball while on the rug. This keeps his
hand busy without causing a distraction while helping him focus.
c) The worksheet is also designed to focus students when they are working in
pairs. This way they know step-by-step what needs to be completed. This
allows them to apply what they learned on the rug without becoming
unfocused with the freedom of the activity.
12) Resources
a) Everyday Mathematics
b) http://www.superteacherworksheets.com/geometry.html