Lesson 81

Routine and Non-Routine Problems involving Areas of Squares and Rectangles

BY: REI MARASIGAN

Drill

Give the most appropriate unit of measure for the following (cm or m).

a. paper clip f. manila paper

b. table g. cartolina

c. book h. telephone wire

d. flag pole i. garden plot

e. shoe box j. floor tile

Review

Motivation

Measure the length and width of our classroom.

What is the area of our room?

Presenting the Lesson

• A room measures 8 meters long and 7 meters wide. What is the area of

the room?

• What is the shape of the room?

(Rectangle)

Draw the figure and put the correct dimensions.

Ask: How do we find the area?

Area = length times width

• write the mathematical sentence and solve.

A = l x w

A = 8 x 7

Ask: What is the unit of measure?

Square meters (sq. m.)

State the complete answer.

The area is 56 square meters

Is this the correct answer? Why?

​

Lito’s vegetable garden measures

5 meters on each side.

• What is the area of the garden?
• What is the shape of the vegetable garden?

Square

• How do we find the area?

Area = side times side

• Let them write the mathematical sentence and solve.

A = s x s

A=5x5

• What is the unit of measure?

Square meters (sq. m.)

• State the complete answer.

The area is 25 square meters

Performing the Activities

Let the pupils solve the following problems by pairs.

1. Mr. Reyes bought a square lot with measures 12 meters on one side.

What is its area?

Draw the figure to find the answer.

Solve the answer using the formula.

State the complete answer.

The area of a rectangular hall is 180 sq. m. If the length is 15

meters long, what is its width?

Draw the figure to find the answer.

Solve the answer using the formula.

State the complete answer.

Reinforcing the Concept

a. Form learning partners. They will play “Math Survival.”

​

1. Call two pairs of contestants.

2. They will be asked to listen to the problem.

3. Without using a ballpen and paper they have to give the answer.

4. The first to give the correct answer remains.

5. The pair who remains will choose their next opponent.

6. Repeat the process until one pair is left.

Sample questions: 1. A handkerchief measures 30 cm on all sides. What is its Area

2. The movie theatre is 20 meters long and 15 meters wide.What is its area?

3. The swimming pool is 12 meters long and 8 meters wide. Find its area.

4. A square garden has 10 meters on each side. What is the area?

5. A park is 35 meters long and 10 meters wide. Find its area.

6. The parking lot is 20 meters on each side. What is its area?

7. Rico made a chopping board which is 20 cm long and 30

cm wide. What is its area? 8. The municipal plaza is 40 meters long and 25 meters wide. Find its area.

Summarizing the Lesson

What is area?

The number of square units needed to cover the region inside a

figure is called area.

How do we find the area of a square and a rectangle?

• To find the area of a rectangle, use the formula Area =length x

width. This formula is often written as A = l x w.

• To find the area of a square, use the formula area = side x side. This formula is often written as A = s x s.

How did we solve the problems involving the area of a rectangle and a square?

• To solve a one step word problem involving the concept of

area, follow the 4-step plan in problem solving, draw the figure

and use the formula in finding the area of a rectangle and a

square.

Applying to New and Other Situations

Lutasin ang sumusunod na suliranin (word problem). Gumuhit

ng ilustrasyon na makakatulong sa iyo.

1) Ano ang lapad ng auditorium kung ang area nito ay 120 sq. m at ang haba nito ay 35 m?

2) Ang aking tiyo ay may 36 sq. m na taniman ng gulay.

Ano ang sukat ng gilid o side nito?

3) Ang area ng isang parihabang lote ay 576 sq. m. Kung

ang lapad nito ay 18 m, ano ang haba nito?

4) Ano ang area ng papel kung ang sukat nito ay 10 cm at 5 cm?

5) Ang area ng isang parisukat na silid ay 9 sq. m. Ano

ang sukat ng gilid o side nito

Evaluation

Bumuo ng mga suliranin gamit ang mga hugis o figure na nasa ibaba. Gamitin ang imahinasyon sa pagbibigay ng pangalan nito ng mga salita tulad ng plot, sakahan, hardin, sahig, damuhan, lote, plaza, at iba pa.

Basahin, unawain, at lutasin.

• 1)Si G. Angeles, may-ari ng isang subdivision sa Cebu

ay nagbigay ng lote para sa simbahan. Ano ang

area ng pagtatayuan ng simbahan kung ang haba

ng lote ay 24 na metro at 30 metro ang lapad?PY

• 2)Gumawa ng bandera si Ken para sa programa ng

paaralan. Ang bandera ay 32 cm ang haba at 25

cm ang lapad. Ano ang area ng bandera?

• 3)Ang area ng parisukat na lote ni G. Devanadera ay

180 sq.m. Ang kay G. Gesmundo ay dalawang beses

ang laki ng kay G. Devanadera, ano ang area ng lote ni

G. Gesmundo?

Home Activity