A middle school math lesson on classifying and measuring angles

1. Classifying Angles
OBJECTIVES:
 I CAN NAME ANGLES IN FOUR DIFFERENT WAYS.
 I CAN CLASSIFY ANGLES AS ACUTE, RIGHT, OBTUSE, OR
STRAIGHT.
 I CAN IDENTIFY VERTICAL AND ADJACENT ANGLES.
 I CAN FIND MISSING MEASURES OF ANGLES

2. Angles
A shape formed by two rays sharing a common endpoint;
contains two rays and a vertex
ray
ray
vertex
vertex—point common to two rays of a
triangle or two sides of a polygon
ray—has one endpoint and goes infinitely
in one direction

3. How are angles used in real life?

4. How are angles used in real life?
Transportation
Architecture &
Engineering

5. Naming Angles
There are 4 ways to name an angle:
 Using the vertex
Example: < O
 Using the number
Example: < 1
 Using the points with
the vertex in the middle
Example: < MOP or < POM

6. Name that angle…
 Using the vertex
 Using the number
 Using the points with
the vertex in the middle

7. There are 4 basic types of angles:
Acute
Right
Obtuse
Straight

8. acute Angle
An acute angle measures less than 90° and looks like this:
It measures more than 0 degrees but less than 90 degrees.
0 < acute angle < 90

9. acute Angles
measures less than 90°

10. Which angles are not acute?
1
2
3
4
5

11. Right Angles
A right angle measures exactly 90° and looks like this:
We draw the square around the right angle so we quickly identify it as a 90° angle. These
angles are the most common in everyday life: the corner of a door, window, table,
piece of paper.

12. Right Angles
measures exactly 90°

13. Which angle is a right angle?
1
2
3
4
5

14. DON’T FORGET this about me…….

15. obtuse Angle
An obtuse angle measures more than 90° and looks like this:
It measures more than 90 degrees but less than 180 degrees.
90 < obtuse angle < 180

16. obtuse Angles
measures more than 90°

17. Which angle is obtuse?
1
2
3
4
5

18. straight Angle
A straight angle measures exactly 180° and looks like this:
It makes a straight line.

19. straight Angles
measures exactly 180°

20. Which angle is a straight angle?
1
2
3
4
5
6

21. Just a little jokey-joke for you:

22. adjacent
Angles
NEXT DOOR NEIGHBOR
Adjacent angles are “side by side” and share a common ray and vertex.

23. These are examples of adjacent angles.
55º
35º
50º130º
80º 45º
85º
20º

24. These angles are NOT adjacent.
45º55º
50º
100º
35º
35º

25. VERTICAL
Angles
OPPOSITES
When 2 lines intersect, they make vertical angles.
Vertical angles are opposite one another.
75º
75º
105º105º

26. Vertical angles are congruent (equal).
30º150º
150º30º

27. Finding the value of a missing measure using what
we know about vertical angles…
 Find the value of x in the figure below.
YOU TRY!_____________________________
 What is the value of x in the figure below?

28. Practice time!
LET’S PLAY A GAME CALLED….
WHAT’S YOUR ANGLE?

29. Exit slip
Show me what you learned today!
Complete the Exit Slip and turn it in to
tray 1 on your way out when I dismiss you.
DON’T FORGET TO DO YOUR HOMEWORK
& COMPLETE HOMEWORK LOG