MATHEMATICS 4 QUARTER 3
WEEK 2 LESSON 49
Describing and Illustrating the Different
Kinds of Angles
MARVIE T.BLANCO
FOUR-KINDNESS
URDANETA I CENTRAL SCHOOL
URDANETA CITY, PANGASINAN
Objective: Describe and illustrate the different angles (right, acute, and obtuse) using models.
I Value Focus: Spending timewisely
Drill
Identify the different kinds of lines.
A.
B.
C.
REVIEW
What is a ray?
Name the given rays?
A
B
D
C
E
F
G
H
Ask the pupils to look at the clock.
Ask: What time is it now? Lead the pupils to discuss what they do during recess time, lunch time, etc. Emphasize the importance of spending time wisely.
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At What time
Performing the Activities
Expected Answers
Let the pupils work in pairs.
Draw the hand position of the clock
Based on the situation given.
EXPLORE and DISCOVER !
Look at the hands of the clock.
Ray AB meets with ray AC at point A. When two rays meet at a common endpoint, they form an angle. Point A, the common endpoint, is called the vertex. An angle can be named in 3 ways.
C
< BAC is read as “ angle BAC”
< CAB is read as “ angle CAB”
< A is read as “ angle A “ or
< 1 is read as “ angle 1”
An angle is measured in degrees (˚) Angles can be classified according to their measurements.
A right angle measures 90˚. It forms a square corner.
An acute angle measures less than 90˚. It is smaller than a right angle.
An obtuse angle measures more than 90 ˚ but less
than 180 ˚
Name the angles below.
What kind of angles are they?
Tell whether each kind of angle is right, acute , or
obtuse.
1.
5.
4.
3.
2.
GET MOVING !
A. Tell whether each kind of angle is right, acute, or obtuse.
1.
2.
3.
4.
5.
B. Draw the following angles.
1.
2.
3.
KEEP MOVING !
Give the kind of angle represented by each of the
following figures.
1.
2.
3.
4.
5.
Lead the pupils to state the following generalizations.
An angle is formed when two rays meet at a common endpoint.
It is measured in degrees ( ˚)
Angles can be classified according to their
measurements. A right angle measures 90˚.It forms a square corner.
An acute angle measures less than 90 °. It is smaller than a right angle. An obtuse angle measures more than 90 °, but is less than 180°.
GENERALIZATION
Applying to New and Other Situations
A. Using the figure at the right, identify if the given
angle (oriented counter clockwise) is right, acute, or obtuse.
1. LAOB A
2.L BOC
3. L DOE F c
4.L FOD
5. L COE
B
O
E
D
B. Group the pupils into six for the "Bring Me Game." Let them bring the object that is required. The first group to bring the object will be given one point.
1. Objects with an acute angle - Example: triangular objects
2. Objects with an obtuse angle - Example: picture stand
3. Objects with a right angle - Example: chair
APPLY YOUR SKILLS
A. Give what is asked for in each item
1. Name 2 objects with right angles.
2. Name 2 objects with acute angles.
3. Name 2 objects with obtuse angles.
B. Draw your dream house using different angles.
Label the angles used.
Assessment
Write the letter of the correct answer.
1. What geometricfigure is formed when two rays meet at a common endpoint?
a. line b. point c. angle d. polygon
2. Which is the same as angle AOB?
a. LOAB b. LOAB c. LBAO d. L O
3. What kind of angle is formed by the corner of a square table?
a. right angle c. obtuse angle
b. acute angle d. none of the above
4. What kind of angle is shown by an opened book whose measure is greater than 90 °?
a. right angle c. obtuse angle
b. acute angle d. right or acute angle
5. What kind of angle is illustrated when the hands of a clock form 1 :20?
a. right angle c. obtuse angle
b. acute angle d. none of the above
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Home Activity
Remediation
Draw a flower if the angle (oriented counter clockwise) shown is an acute angle, a star if it is a right angle, or a diamond if it is an obtuse angle.
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Enrichment:
Study the illustration. E
1. Name 5 acute angles.
2. Name 2 right angles. F
3. Name 3 obtuse angles.
C