Download Lesson Plan 1

TITLE:
Classifying different types of triangles
PURPOSE:
In this lesson, students will create many different triangles, while
measuring each of the triangles’ angles. The students will then determine
the type of each triangle (acute, obtuse, right, scalene, equilateral, and
isosceles). From this, the students will be able to identify the various
angles and discuss their measures in relation to the various types of
triangles.
STANDARDS:
Students will reason and evaluate mathematical arguments.
a. Recognize reasoning and proof as fundamental aspects of mathematics.
b. Make and investigate mathematical conjectures.
c. Develop and evaluate mathematical arguments and proofs.
d. Select and use various types of reasoning and methods of proof.
OBJECTIVES:
 Students will learn the components of an acute, obtuse, and right triangle.
 Students will learn the difference between an equilateral, scalene, and isosceles
triangle.
 Students will discover the total measurement of the interior angles of triangles is
always 180 degrees.
 Students will learn how to draw different triangles is GSP, along with learning
how to use the measurement tools.
ESSENTIAL QUESTIONS:
 What is a triangle?
 What is an acute triangle? Obtuse? Right? Scalene? Isosceles? Equilateral?
 What is the total measurement of the interior angles of a triangle?
MATERIALS:
 Pencil
 Paper
 Computers with GSP (one computer for every two student)
PROCEDURES:
1. Review the different types of angles on the board, by having the students
volunteer the names of the different types of angles. (5 min)
2. Have a few students come to the board and draw an acute, obtuse, and right
triangle. Then discuss what makes each triangle. (5 min)
3. We will talk about the definitions for each type of angle and the students will
write the definitions in their notes. (5 min)
4. Have the students draw an acute, obtuse, and right triangles on their own piece of
paper, having the students label each type of triangle. (5 min)
5. Next we will discuss how to classify the different types of triangles based on their
sides (scalene, isosceles, and equilateral). The students will then write the
definition of triangles based by their sides in their notes. (5 min)
6. We will then make a connection between the angle measures and the side lengths.
The students will then write the classifications in their notes. (15 min.)
7. Go to lab (5 min)
8. Have the students draw the different types of triangles in GSP (obtuse, acute,
right, equilateral, scalene, and isosceles). (25 min.)
9. Then, have the students click on each vertex and then go to the MEASURE
button in the menu to measure the angles of each triangle and repeat the procedure
until all three angles have been measured in each triangle. (20 min.)
10. Then, have the students calculate the measurements of all three angles to find out
the total measurement of the interior angles. (10 min)
11. Have students print out the different triangles along with their each of the
measurements for the triangles that they constructed in GSP. (5 min)
ASSESSMENT:
After collecting the GSP constructions, I will check to make sure the students
identified/classified the six types of triangles correctly. For those students who showed
they understood the components of the different types of triangles, I will have them
continue on exploring triangle properties by having the students do the extension.
However, for the students who were unable to identify or incorrectly identified the six
types of triangles, I will do a small group re-teaching of the lesson using marker boards.
This will allow the students to interact one-on-one with myself and others, while trying to
figure out the components for certain types of triangles.
EXTENSION:
Have the students explore to see which types of triangles (with different angles and side
lengths) can exist.
REFLECTION:
After completing the lesson, students were able to correctly identify the different types of
types of triangles. I feel that it would have also been helpful if I had the student cut out
the angles of the triangle and then lay them out so they could visually see that the angles
in the triangle add up to 180 degrees.