1. Fifth Grade, Geometry Section Lesson 3
Exploring Angles

2. It’s time to pass out triangles and protractors.
Let’s begin with an activity…
It’s time to pass out triangles and protractors.

3. We recently learned how to:. . classify and describe lines. 
We recently learned how to:  classify and describe lines  name and describe angles  measure angles

4. Here is our triangle

5. Here is our triangle after tearing in pieces

6. We need to line up the angles

7. Here is a right triangle
How does it compare to a the isosceles triangle?

8. This is an acute triangle
This acute triangle is also a scalene which means that no angles or sides are the same
Every angle is 90
What is the sum of all the angles?
80 + 45 + 55 = 180

9. This is a right triangle
Has exactly one right angle
What is the sum of all the angles?
90 + 30 + 60 = 180

10. This is an isosceles triangle
At least two angles are the same and every angle is 90
How much is the missing angle?
180 - 64 - 64 =
52

11. This is a right isosceles triangle
Isosceles means it has at least two equal sides/angles
Has exactly one right angle
What is the sum of all the angles?
90 + 45 + 45 = 180

12. This is an obtuse triangle
Has exactly one obtuse angle
What is the sum of all the angles?
110 + 50 + 20 = 180

13. This is an equilateral triangle
Has exactly three equal sides
Has three equal angles
If every angle is the same, what is it?
180  ÷ by 3 = 60

14. It’s time to Pass out the photographs and markers
Let’s see if we can identify shapes…
It’s time to Pass out the photographs and markers

26. It’s time to pass out the worksheet and do the first one together
Let’s begin our assignment…
It’s time to pass out the worksheet and do the first one together

27. It’s time to flip the photograph over for a few practice questions
Let’s finish with a few questions
It’s time to flip the photograph over for a few practice questions

28. Practice TAKS Style Questions:
A triangle has angles, J, K, and L, m J is 58, and K is larger than J. Which of the following is not a possible measure for L? J
A. 58
B. 32
C. 70
D. 51.5 K L

29. Practice TAKS Style Questions:
Classify the triangle.
A. Right triangle
B. Obtuse triangle
C. Acute triangle
D. Equilateral triangle

30. Practice TAKS Style Questions:
How many obtuse angles can a
triangle have?
A. 1
B. 2
C. 3
D. 4