Triangle Classification Project
Directions and Rubric
Project Directions:
Step One: Cut out the nine triangles from the Triangles for Classification Activity
worksheet.
Step Two: Classify each triangle by its sides and angles. Clearly write the classifications
directly onto the triangle.
Step Three: Glue the triangles onto the piece of construction paper.
Step Four: Write a title onto your classification project.
Step Five: Write all of the group member names onto the project.
Scoring Rubric
3 Points – A title is included. All triangles are neatly glued onto the construction paper
and clearly labeled with the correct side classification and angle classification. All team
member names are written on the project.
2 Points - A title may or may not be included. All triangles are neatly glued onto the
construction paper and clearly labeled with the side and angle classifications. There are
up to two classification errors. All team member names are written on the project.
1 Point - A title may or may not be included. All triangles are glued onto the construction
paper and labeled with the side and angle classifications. There may be up to 3 incorrect
classifications. All team member names are written on the project.
Classifying Triangles by their Angles
#1
#2
#3
What do you notice about the
lengths of the sides of the
triangle below?
________________________
What do you notice about the
lengths of the sides of the
triangle below?
________________________
What do you notice about the angles
in the triangle below?
Classifying Triangles by their Sides
#1
#2
#3
How many degrees
are in a triangle?
Answer Key
A
B
C
Directions:
1. Highlight each of the vertices of triangle ABC with your highlighter.
2. Cut out triangle ABC.
3. Then, cut off each of the angles of the triangle by cutting on the dotted line.
4. Line up the detached angles so that angle A is adjacent to angle B and angle C is
adjacent to angle B.
A B C
Students should
line up the pieces
like this.
What do you notice about the new angle formed by angles A, B, and C? What kind of
angle is formed?
The new angle formed by angles A, B and C forms a straight line which is a straight
angle.
What is the sum of the angles in the triangle?
The triangle has 180˚.
Do you think that this always happens or that it just happened this time?
Answers will vary.
How many degrees
are in a triangle?
A
B
C
Directions:
5. Highlight each of the vertices of triangle ABC with your highlighter.
6. Cut out triangle ABC.
7. Then, cut off each of the angles of the triangle by cutting on the dotted line.
8. Line up the detached angles so that angle A is adjacent to angle B and angle C is
adjacent to angle B.
What do you notice about the new angle formed by angles A, B, and C? What kind of
angle is formed?
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
What is the sum of the angles in the triangle?
________________________________________________________________________
Do you think that this always happens or that it just happened this time?
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
Missing Angle Journal Entry
Answer Key
You just learned that all triangles have a sum of angles that is equal to 180 degrees. With
that information, you can find a missing angle in a triangle if you know the other two
angle measures. Demonstrate and explain, using words, symbols, pictures and numbers,
how you would find the third angle in a triangle where the other angles are 18˚ and 46˚.
Use the box below to show all work and then explain how you found the missing angle
on the lines below.
Show your work here: Answers will vary.
Sketch of triangle –
180 total degrees
-46
-18
?
116 degrees
46
18
Explain how you found your answer below:
First, I added 46 degrees and 18 degrees to find out the total degree measure of the two
angles. That gave me 64 degrees. Next, I subtracted that from the total 180 degrees that
make up the triangle to get my answer of 116 degrees.
Missing Angle Journal Entry
You just learned that all triangles have a sum of angles that is equal to 180 degrees. With
that information, you can find a missing angle in a triangle if you know the other two
angle measures. Demonstrate and explain, using words, symbols, pictures and numbers,
how you would find the third angle in a triangle where the other angles are 18˚ and 46˚.
Use the box below to show all work and then explain how you found the missing angle
on the lines below.
Show your work here:
Explain how you found your answer below:
______________________________________________________
______________________________________________________
______________________________________________________
______________________________________________________
______________________________________________________
______________________________________________________
______________________________________________________
______________________________________________________
What do you notice about the angles
in the triangle below?
What do you notice about the angles
in the triangle below?
What do you notice about the
lengths of the sides of the
triangle below?
________________________
Triangle Exit Quiz
Answer Key
Directions: Classify each of the triangles below by their angles and sides. Write directly
inside the triangles.
1.
2.
Right, scalene
3.
acute, isosceles
obtuse, scalene
Directions: Find the missing angle.
4. Angle 1 = 32˚
Angle 2 = 111˚
Angle 3 = 37˚
5. Angle 1 = 136˚
Angle 2 = 22˚
Angle 3 = 22˚
Triangle Exit Quiz
Directions: Classify each of the triangles below by their angles and sides. Write directly
inside the triangles.
2.
2.
3.
Directions: Find the missing angle.
4. Angle 1 = 32˚
Angle 2 = 111˚
Angle 3 = ?˚
5. Angle 1 = ?˚
Angle 2 = 22˚
Angle 3 = 22˚
Triangles for Classification Activity