Lesson Notes By Weeks and Term - Senior Secondary 1

Enlargement and reduction of plain figures 1

TERM – 2ND TERM

WEEK SIX

Class: Senior Secondary School 1

Age: 15 years

Duration: 40 minutes of 5 periods each

Date:

Subject: Technical Drawing

Topic: ENLARGEMENT AND REDUCTION OF PLAIN FIGURES 1

SPECIFIC OBJECTIVES: At the end of the lesson, pupils should be able to

I.) Differentiate between enlargement and reduction

II.) Describe the applications of enlargement and reduction

INSTRUCTIONAL TECHNIQUES: Identification, explanation, questions and answers, demonstration, videos from source

INSTRUCTIONAL MATERIALS: Videos, loud speaker, textbook, pictures,

INSTRUCTIONAL PROCEDURES

PERIOD 1-2

 PRESENTATION TEACHER’S ACTIVITY STUDENT’S ACTIVITY STEP 1 INTRODUCTION The teacher explains and identify enlargement and reduction ratios. Students listens attentively to the teacher STEP 2 EXPLANATION Teacher discusses the applications of enlargement and reduction. Students exhibit attentiveness and active engagement STEP 3 NOTE TAKING The teacher writes a summarized note on the board The students copy the note in their books

NOTE

ENLARGEMENT AND REDUCTION OF PLAIN FIGURES 1

Enlargement of plane figures

Enlargement of plane figures involves increasing the size of a shape while maintaining its proportions. This means that all lengths, angles, and ratios within the figure are scaled up by the same factor, resulting in a larger version of the original shape. It's commonly done by multiplying the coordinates of each point in the figure by the scale factor.

Enlargement ratios can vary widely depending on the specific enlargement being performed. Common enlargement ratios include:

1. 2:1 (doubling in size)
2. 3:1 (tripling in size)
4. 5:1 (increasing by a factor of 5)
5. 10:1 (increasing by a factor of 10)

Reduction of plane figures

Reduction of plane figures involves decreasing the size of a shape while preserving its proportions. Like enlargement, all lengths, angles, and ratios within the figure are scaled down by the same factor, resulting in a smaller version of the original shape. This process is typically achieved by dividing the coordinates of each point in the figure by the scale factor.

Reduction ratios indicate how much smaller a figure becomes after reduction. Like enlargement ratios, they can be expressed as a fraction or a decimal. Below are some common reduction ratios:

1. 1:2 (halving in size)
2. 1:3 (reducing to one-third of its original size)
3. 1:4 (reducing to one-fourth of its original size)
4. 1:5 (reducing to one-fifth of its original size)
5. 1:10 (reducing to one-tenth of its original size)

Application of enlargement and reduction

Applications of enlargement and reduction of plane figures include:

1. Architecture and Engineering: Enlarging or reducing blueprints and models of buildings to fit different scales or purposes.
2. Cartography: Enlarging or reducing maps to show details at different levels of magnification.
3. Graphic Design: Adjusting the size of images or designs for various mediums such as posters, banners, or advertisements.
4. Education: Teaching geometric concepts by visually demonstrating the effects of enlarging or reducing shapes.
5. Photography: Enlarging or reducing images for printing or digital display..
6. Geography: Creating accurate representations of geographical features and landforms at different scales.

EVALUATION: 1. What is difference between enlargement e reduction.

1. Identify 5 enlargement and reduction ratios.
2. Mention 5 applications of enlargement and reduction.

CLASSWORK: As in evaluation

CONCLUSION: The teacher commends the students positively