lesson in math

1. Lesson 51:Identifying and Describing Triangles
MARVIE T.BLANCO
FOUR-KINDNESS
URDANETA I CENTRAL SCHOOL
URDANETA CITY,PANGASINAN

2. Objective : Identify and describe triangles
according to sides and angles.

3. Value focus : patriotism

4. A . Preliminary Activities
1.Drill[answer in the whiteboard]
Draw the polygon or lines described.
A)A plane figure with 3 sides and 3 angles.
B)A plane figure with 4 sides and 4 angles.
C)Lines that do not meet.
D)Lines that cross each other.
E)Lines that intersect and form square
corners .

5. 2.Review:1]What is a triangle?
A triangle is a plane figure with 3 sides and 3 angles.
2]What is a quadrilateral?
A quadrilateral is a plane figure with 4 sides and 4 angles.

6. 3.Motivation:
Ask : What can you see in the flag?
What plane figure can you see?
How do we show respect to the Phil. Flag?
What are the ways to show patriotism or
loyalty to our country?

7. B . Developmental Activities
1.Presentation
Miss Fina assigned some of her pupils to
bring different objects with the shape of a
triangle . Benilda brought a picture of a house ,
Grace showed a picture of a road sign , and
Jocelyn prepared a triangular flaglet .
Triangular
flaglet
Observe the different
triangular objects . How will
you describe the different
triangular objects?

8. 2.Performing the Activities [team work]
Classify the following cutouts into 2 groups
and describe them according to their sides
and angles.

9. 3.Processing the Activities[observe the different
triangles]
Do all triangles have equal sides? Do
they all have equal angles
DISCUSSION
Triangles can be classified according to sides.
A) An equilateral triangle has 3 equal sides.
B). An isosceles triangle has 2 equal sides.
C). A scalene triangle has no equal sides.

10. Triangles can be classified according
to their angles.
1) A right triangle has a right
angle which measures 90˚.
2) An acute triangle has 3
acute angles , each measuring less
than 90˚.
3) An obtuse triangle has an
obtuse angle which measures more
than 90.˚

11. 4.Reinforcing the Concept and Skill
Discuss the presentation under Explore and
discover on page 162 of the LM.

13. B. Answer the following questions.
Draw a circle if your answer is Yes or a
diamond if it is no.
1]Does an isosceles triangle have 2 equal
sides.
2]Does an acute triangle have an obtuse
angle.
3]Does an equilateral triangle have equal
sides.

14. 4]Does an scalene triangle have no equal
sides.
5]Does a right triangle have a right angle.
6]Does an obtuse triangle have an acute
angle?

15. C . Keep Moving !page 163 of LM
Answer the following questions.
1.How many equal sides does an
isosceles
triangle have.
2.How many equal sides does an
equilateral
triangle have?
3.What kind of angle does an
acute triangle

16. 5.Generalization:
How are triangles classified ?
Triangles can be classified according to
angles as right , acute, or obtuse triangle . It
can also be classified according to sides as
equilateral, scalene, or isosceles triangle.

17. 6.Applying to New and other Situations.
A]Choose the correct answer. Write your answer in
your notebook.[right triangle ,acute triangle, scalene
triangle, obtuse
triangle , isosceles triangle or equilateral triangle]
1.A triangle which measures 90º is ______________.
2.A triangle which has no congruent angles is
_____________.
3.A triangle which has 90º angle is ________________.
4.A triangle with three congruent angles of the same
measurement is ______________.
5.A triangle with two congruent angles and two
congruent sides
Is ______________.
6.A triangle that has more than 90º angles is

18. Do “Apply Your Skills” on page 163
Using old calendars, cut out triangles.
Classify them
according to sides and angles.

19. C. Assessment
Name the triangle described in each
item.
1.It is a triangle which has a right angle.
2.It is a triangle which has an obtuse
angle.
3.It is a triangle which has 3 acute angles.
4.It is a triangle which has 3 acute angles.
5.It is a triangle which has no equal sides.
6.It is a triangle which has 3 equal sides.

20. D . Home Activity [Remediation]
Draw the following triangles correctly.
1. Right triangle 4.Equilateral triangle
2.Obtuse triangle 5.Isoscles triangle
3.Acute triangle 6.Scalene triangle

21. Enrichment : DAY 1
Draw the following figures with the indicated
measurement:
1.Equilateral triangle , each side measures 5 cm.
2.Isosceles triangle , equal sides measure 4cm each,
one side measures 6 cm.
3.Scalene triangle , side A measures 6cm, side B
measures 7cm,side C measures 4cm.
4.Right triangle
5.Obtuse triangle,110˚
6.Acute triangle, 70˚

22. ENRICHMENT DAY 2
Draw the following triangles.
1.Equilateral triangle
2.Acute triangle
3.Scalene triangle
4.Right triangle
5.Isosceles triangle
6.Obtuse triangle

23. ENRICHMENT :DAY 3

25. ENRICHMENT :DAY 4

26. THANK YOU SO MUCH !
MARVIE T.BLANCO
FOUR-KINDNESS
URDANETA I CENTRAL SCHOOL
URDANETA CITY,PANGASINAN