Download Triangles, Triangles!

Math 5 Standard 4 Combo
1/7/03
10:42 AM
Page 149
Standard Indicator
5.4.2
Triangles, Triangles!
Purpose
Students will identify, draw, and classify triangles as equilateral,
isosceles, scalene, right, acute, obtuse, and equiangular.
Materials
For the teacher: copy of Black Line Master (BLM) Quilt Designs
For each student: copy of BLM Quilt Designs, colored pencils or
markers, protractors, rulers, drawing paper, pencils
Activity
B. Teacher-Led Activity
1. Direct students to find right angles in the first design. Have them
put a mark in each right angle to look like a small right angle
( ).
2. Have students find a triangle that has an acute angle and a right
angle. Ask students to measure the three sides of this triangle.
Say: “If two sides are the same, we call it a right isosceles triangle.
If your triangle does not have two sides the same, look for one
that does.”
3. Direct students to find two examples of right isosceles triangles
of different sizes.
4. Say: “In the second design, look for a triangle with all its angles
acute. Measure the sides of this triangle.” When students find
that this triangle has two sides the same length, tell them that
this makes it an acute, isosceles triangle.
5. Say: “Find an obtuse angle in the second design and look at the
triangle that it is in. What do you notice about the other two
angles?” [They are acute.] Tell students that just one obtuse angle
makes this an obtuse triangle.
(continued)
Standard 4 / Curriculum Framework / Activity 2
Indiana Mathematics Grade 5 Standards Resource, February 2003
ACTIVITY
Find other quilt designs
(e.g., in the book
Quilt Square Design
Masters by Luanne
Seymour Cohen) or
actual quilts, and have
students find the kinds
of triangles and other
shapes in them.
connecting
across the
curriculum
Visual Arts
Have students make and
color their own quilt
designs, describing the
shapes that they use.
Standards Links
5.4.1, 5.4.3, 5.4.4, 5.4.7
page 149
Standard 4
A. Introduction
1. Assign students to groups of three or four. Give each student a
copy of the BLM Quilt Designs. Tell students that the first design
is called the Pinwheel Square and the second is called the
Whirling Star. Ask why they think they are given those names.
2. Review the different types of angles: acute, right, and obtuse.
3. Explain to students that they are going to look for these in the
quilt designs.
extending
THE
Math 5 Standard 4 Combo
1/3/03
3:39 PM
Page 150
Activity (continued)
6. Ask students to measure the sides of their obtuse triangles. Say:
“Your numbers are probably different. When a triangle’s sides are
different, it is called a scalene triangle. This triangle is also
obtuse because of the angle. We call this triangle obtuse, scalene.”
7. Say: “When we talk about different kinds of triangles, we talk
about them according to their angles and according to their sides,
so every triangle has two names.”
8. Ask students to try to find an equilateral triangle. They should
not find one, so ask them to draw one in each of the squares in
the first design.
Standard 4
C. Group Activity
1. Have students complete the BLM.
2. On separate paper, have students work in their groups to make
as many different kinds of triangles as possible. Expect them to
draw acute scalene, acute isosceles, acute equilateral (also called
equiangular), obtuse scalene, obtuse isosceles, right scalene, and
right isosceles. You may have to help them in order to obtain the
full list of triangles.
3. Allow students to share their findings and their work.
Questions for Review
Basic Concepts and Processes
During the activity, discuss the following questions with your
students:
What are the different ways of naming triangles?
What kind of triangle is this [indicate triangle on BLM]?
Show me an obtuse angle on the BLM.
Tell me why this is a [insert side-name, angle-name] triangle.
page 150
Standard 4 / Curriculum Framework / Activity 2
Indiana Mathematics Grade 5 Standards Resource, February 2003
Math 5 Standard 4 Combo
1/3/03
3:39 PM
Page 151
Name:
Quilt Designs
Quilt Square:
Pinwheel Square
Color the smaller isosceles
right triangles green.
Color the larger isosceles
right triangles blue.
Color the scalene right
triangles red.
Quilt Square:
Whirling Star
First, color the isosceles
right triangles green.
Color the other isosceles
triangles blue.
Color the obtuse scalene
triangles red.
Standard 4 / Curriculum Framework / Activity 2
Indiana Mathematics Grade 5 Standards Resource, February 2003
Black Line Master 1
page 151
Math 5 Standard 4 Combo
1/3/03
3:39 PM
Page 152
Quilt Designs
Teacher Directions
Distribute one copy of the BLM Quilt Designs to each student. Use the BLM as described
in the Teacher-Led and Group Activities.
Answer Key
Colors: R = red
B = blue
G = green
Pinwheel Square:
G
N
Whirling Star:
G
R
B
B
B
N
N
Black Line Master 1
page 152
G
R
R
B
B
B
G
R
B
B
B
N
G
B
B
R
R
B
B
G
G
R
B
R
B
B
B
R
B
G
R
G
G
B
R
R
R
N
B
G
R
N = not colored
R
G
R
Standard 4 / Curriculum Framework / Activity 2
Indiana Mathematics Grade 5 Standards Resource, February 2003