This is my chosen topic for my final demo in practice teaching. "FINDING THE AREA OF A TRIANGLE"

1. Semi-detailedLessonPlaninMathematicsIV
I. OBJECTIVE
Findthe area of a triangle.
II.PREREQUISITE CONCEPTSANDSKILLS
a. Topic:Findingthe Areaof a Triangle
b. References:MathematicsIV Learner’sGuide,pages205-208, MathematicsForLife 4, pages
225-226, Internet
c. Materials:BigParty Hat, Coloredpapers,Ruler,activitysheets forgroupings,laptopand
projector
d. Values:Perseveranceand cooperation
III.INSTRUCTIONALPROCEDURE
A. PreliminaryActivities
1. SPAD
Yaya Dub needstocleanthe garden.The garden isinparallelogramshaped.If the basedis
12 metersandthe heightis6 meters.Finditsarea.
2. Drill
Solve the followingnumbersentencesusingmultiplicationanddivision.
1. 8 x 4 ÷ 2 = n
2. (5)(8)
2
3. 12 x 3
2
4. 10 x 5 ÷ 2 = n
5. 3 x 4 ÷ 2 = n
3. Review
Findthe area of each parallelogram.
= n
= n
b = 6m
h = 4m
b = 3cm
h = 8cm

2. B. DevelopmentalActivities
1. Motivation
Ask:
- What isthe shape of the hat Billywantsforhiscostume?
- Measure the base and the heightof the hat.
What isthe height?Whatisthe base?
2. Presentation
Vocabularywords:
AREA - a part or sectionwithinalargerplace.
TRIANGLE – a shape thatmade up of 3 lines,3 anglesand3 sides.
FINDINGTHE AREA OF A TRIANGLE
So,the area infindingthe areaof a triangle isA =
𝑏ℎ
2
or A=
1
2
(bh) , where b= base andh = height.
Examples:
Billywantstobuy a triangularhatfor hiscostume.He goesin a
supermarketandthere he findssomanyhats. HelpBillytofindthe hat he
wantsfor hiscostume.
b= 6cm h = 6cm
If we have twotrianglesandtheycombined
together.We formedaparallelogram, thus,
triangle ishalf of a parallelogram.
The area in findinga
parallelogramisA = bh
3cm
A = bh/2
A = 6cm x 3cm / 2
A = 1 sq cm
2. A = bh/2
A = 8m (3m)/2
A = 12 sqm

3. 1.
3. Application
- Divide the classinto4.
Group 1: Draw a righttriangle.Label the base andheightas12 cm and4 cm. Findthe area.
Group 2: Vince issurveyingaplotof landinthe shape of triangle.The areaof the land is24
square meters.If the heightmeasured4meters.Whatisthe base?
Group 3: A 10 metersladderisleaningagainstthe building.The bottomof the ladderis 5
metersawayfrombuilding.Whatisthe area of the space of the ladder?
Group 4: whatisthe heightof a triangle withabase of 5 inchesandan area of 20 square
inches?
4. Generalization
The formulainfindinganarea of a triangle isA = bh/2or A = ½ bh where b= base and h =
height.
The formulainfindingthe missingheightandbase of a triangle is:
b = A(2)/handh = A(2)/b
IV.EVALUATION
Solve the following.
1.
Ss
V.HOME ACTIVITY
Complete the table below.
Triangle Base (b) Height (h) Area
1 4 m 2 m
2 6 cm 4 cm
3 12 in 84 sq in
4 12 m 36 sq m
5 9 dm 10 dm
6cm 8m
3m
h = 4m
b = 6m
A =?
A = 3 sq m
b = 2m
h =?
2. 3.
h = 5cm
A = 10 sqcm
b =?