Types of
Triangles
Geometry
Investigation
Activity
Teacher Instructions
•
Materials Needed for this Activity:
o Protractors(These can be printed from
online)
o Website with free printable protractor:
o http://i.infopls.com/scottforesman/Math
_6_TTT_17.pdf
o Rulers
This activity could be used as an introductory
lesson/activity before teaching types of
triangles.
Directions:
1.
2.
3.
4.
5.
6.
I would print the triangles ahead of time on card
stock and place them in plastic bags or envelopes.
I usually complete this activity in groups of 3-4
students.
I pass out one set of the 4 triangles per group. Each
student will need a ruler & protractor.
I set a timer for approximately 15-20 minutes for
students to make all of the their measurements and
fill in the table and answer the questions on the
front.
For early finishers, I have them work on the back
using the chart to help them with the names of the
types of triangles.
There are 2 versions of the chart:
1.
One has definitions of each type of triangle
already matched together.
2.
The second version has students match the
word with the definition.
Types of
Triangles
Geometry
For this resource:
--You must have access to the Internet and a FREE Google account
to use this resource.
--All students will need their own Google account in order to
complete this investigation.
--Click the link below to open the google slides activity where you
can make your own copy by selecting “MAKE A COPY”. The copied file
will appear in your Google Drive. You must be logged into your
google account to do this.
Link to access the Google Slides Presentation:
Don’t have a Google account? Sign up here.
Need help setting up Google Classroom? Check out this quick
tutorial.
Investigation
Activity
Name:____________________ Date:_________
Investigating Types of Triangles
Directions: Measure the sides and angles of each triangle in
CENTIMETERS and DEGREES. Use the protractor to measure the
angles and a ruler to measure the side lengths. Fill in the table for
the appropriate triangle. Work together in the group. Each person
can measure one triangle and share the results with each other.
# of
Triangle
Side
Length
(cm) To
nearest
½ cm
Side
Side
Length Length
(cm) To (cm) To
nearest nearest
½ cm
½ cm
Angle
Measure
degrees
To
nearest 5
degrees
Angle
Measure
degrees
To nearest
5 degrees
Angle
Measure
Degrees
To nearest
5 degrees
1
2
3
4
--After completing the table, answer the following questions.
1.) What do you notice about the 1st triangle’s sides? Angle measurements?
2.) What do you notice about the 2nd triangle’s sides? Angle measurements?
3.) What do you notice about the 3rd triangle’s sides? Angle measurements?
4.) What do you notice about the 4th triangle’s sides? Angle measurements?
--Use the terms below to name each triangle based
on the measurements of the angles and the sides.
•
•
•
•
•
•
scalene—no sides are congruent
obtuse—one angle is greater than 90 degrees
isosceles—two sides are congruent
right—one angle is 90 degrees
equilateral—all sides are congruent
acute—all angles are less than 90 degrees
--Fill in the table below based on the terms in the box
above. It should have two names, one for the angle
measurements, and one the side measurements.
Triangle #
1
2
3
4
Name from
Angles
Name from
Sides
Draw a
picture(include
congruency
markings for
angles and
sides)
--Write the term that matches the correct
definition. Each term will be used ONCE.
•
•
•
•
•
•
1.________________no sides are congruent
2.________________one angle is greater than
90 degrees
3.________________two sides are congruent
4.________________one angle is 90 degrees
5.________________all sides are congruent
6.________________all angles are less than 90
degrees
•
acute
•
Scalene
•
Obtuse
•
Equilateral
•
Right
•
isosceles
--Fill in the table below based on the terms in the box above. It should have two
names, one for the angle measurements, and one the side measurements.
Triangle #
1
2
3
4
Name from
Angles
Name from
Sides
Draw a
picture(include
congruency
markings for
sides.)
Equilateral, Acute Triangles to Cut Out
1
1
1
1
1
1
1
1
Obtuse, Scalene Triangles to Cut Out
2
2
2
2
2
2
2
2
Right, Isosceles Triangles to Cut Out
3
3
3
3
3
Right, Isosceles Triangles to Cut Out
3
3
3
Right, Scalene Triangles to Cut Out
4
4
4
4
4
4
4
4
Answer Key
Types of
Triangles
Investigation
These are
approximations as
everyone measures
differently and all
rulers are not exactly
the same.
Investigating Types of Triangles
Directions: Measure the sides and angles of each triangle in
CENTIMETERS and DEGREES. Use the protractor to measure the
angles and a ruler to measure the side lengths. Fill in the table for
the appropriate triangle. Work together in the group. Each person
can measure one triangle and share the results with each other.
# of
Triangle
Side
Length
(cm) To
nearest
½ cm
Side
Side
Length Length
(cm) To (cm) To
nearest nearest
½ cm
½ cm
Angle
Measure
degrees
To
nearest 5
degrees
Angle
Measure
degrees
To nearest
5 degrees
Angle
Measure
Degrees
To nearest
5 degrees
1
6 cm
6 cm
6 cm
60°
60°
60°
2
4 cm
6.5 - 7
cm
8.5 cm
20°
50°
110°
3
8 – 8.5
cm
8 – 8.5
cm
12 cm
45°
45°
90°
4
4 cm
7 – 7.5
cm
8 cm
30°
60°
90°
--After completing the table, answer the following questions.
Answers may vary.
1.) What do you notice about the 1st triangle’s sides? Angle measurements?
All the sides & angles are the same.
2.) What do you notice about the 2nd triangle’s sides? Angle measurements?
All the sides and angles are different. One angle is over 90°.
3.) What do you notice about the 3rd triangle’s sides? Angle measurements?
Two of the sides and angles are the same. One angle is 90°.
4.) What do you notice about the 4th triangle’s sides? Angle measurements?
All the sides are different. There is a 90° angle.
--Use the terms below to name each triangle based
on the measurements of the angles and the sides.
•
•
•
•
•
•
scalene—no sides are congruent
obtuse—one angle is greater than 90
degrees
isosceles—two sides are congruent
right—one angle is 90 degrees
equilateral—all sides are congruent
acute—all angles are less than 90 degrees
--Fill in the table below based on the terms in the box
above. It should have two names, one for the angle
measurements, and one the side measurements.
Triangle #
Name from
Angles
Name from
Sides
1
Acute
Equilateral
2
Obtuse
Scalene
3
Right
Isosceles
4
Right
Scalene
Draw a
picture(include
congruency
markings for
angles and
sides)
--Write the term that matches the correct
definition. Each term will be used ONCE
•
•
•
•
•
•
scalene
1.________________no
sides are congruent
obtuse
2.________________one
angle is greater than 90
degrees
isosceles
3.________________two
sides are congruent
right
4. ________________one
angle is 90 degrees
equilateral sides are congruent
5.________________all
acute
6.________________all
angles are less than 90 degrees
•
acute
•
Scalene
•
Obtuse
•
Equilateral
•
Right
•
isosceles
--Fill in the table below based on the terms in the box above. It should have two
names, one for the angle measurements, and one the side measurements.
Triangle #
Name from
Angles
Name from
Sides
1
Acute
Equilateral
2
Obtuse
Scalene
3
Right
Isosceles
4
Right
Scalene
Draw a
picture(include
congruency
markings for
angles and
sides)
Thanks
Thanks so much for downloading this
product. I hope you and your students
enjoy this activity.
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