Lesson Plan | Lesson Plan Tradisional | Expansion and Reduction of Figures

Objectives

Duration: (10 - 15 minutes)

The aim of this lesson plan stage is to lay a solid groundwork on the concepts of enlargement and reduction of geometric shapes. Grasping how area and perimeter values are impacted by proportional changes in the sides of figures is vital for sharpening students' mathematical capabilities, enabling them to utilize these concepts in both practical and theoretical problems.

Objectives Utama:

1. Explain how the areas and perimeters of geometric shapes change when the sides are increased or decreased in proportion.

2. Accurately calculate the area and perimeter values of geometric shapes after increasing or decreasing their sides.

Introduction

Duration: (10 - 15 minutes)

📚 Purpose: The objective of this stage is to create a clear and captivating context that hooks students' interest and gets them ready to understand how the areas and perimeters of geometric figures are affected by proportional changes in their sides. This foundational knowledge is crucial for students as they progress through the lesson.

Did you know?

🔍 Did you know?: Enlargement and reduction of shapes aren't just for photos. In architecture, for instance, engineers and architects use scales to create smaller models of buildings before scaling them up to full size in actual construction. Similarly, on maps, we use scales to depict large areas on a small page.

Contextualization

👋 Welcome to Maths class! Today, we're diving into an engaging and practical concept: enlargement and reduction of geometric shapes. Picture you have a photo and want to enlarge it to fit a bigger frame or shrink it to fit a smaller one. What happens to its dimensions? And to the area it covers? These are the concepts we'll explore and apply during our lesson.

Concepts

Duration: (40 - 50 minutes)

📚 Purpose: The goal of this stage is to give students a comprehensive and practical understanding of the concepts of enlargement and reduction of geometric shapes. By tackling specific topics and solving real-world problems, learners will be equipped to apply their newfound knowledge to calculate areas and perimeters after proportional adjustments to their sides.

Relevant Topics

1. Proportionality: Discuss that proportionality refers to the relationship between two quantities that change in a consistent manner. Illustrate how this applies to the enlargement and reduction of shapes, meaning all sides of a shape increase or decrease by the same proportion.

2. Enlargement of Shapes: Explain that when enlarging a shape, the sides are multiplied by a factor greater than 1. Provide visual examples of enlarged squares and rectangles and explain how to compute the new area and perimeter.

3. Reduction of Shapes: Describe that when reducing a shape, the sides are multiplied by a factor less than 1. Show visual examples of reduced shapes and demonstrate how to determine the new area and perimeter.

4. Calculating Areas and Perimeters: Show how to calculate the area (side x side for squares, base x height for rectangles) and perimeter (sum of the sides) of shapes before and after enlargement or reduction.

5. Practical Examples: Work through problems step-by-step on the board, illustrating clearly how to apply proportionality concepts to calculate the new area and new perimeter after altering the sides.

To Reinforce Learning

1. If a square with a side of 4 cm is enlarged by a scale factor of 3, what will be the new area and perimeter?

2. A rectangle measures 6 cm by 8 cm. If it's reduced by a scale factor of 0.5, what will the new area and perimeter be?

3. A triangular shape has sides measuring 5 cm, 5 cm, and 5 cm. If these sides are enlarged by a scale factor of 2, what will the new perimeter be?

Feedback

Duration: (20 - 25 minutes)

📚 Purpose: This stage aims to recap and solidify the knowledge gained throughout the lesson, ensuring that students know how to apply the concepts of enlargement and reduction of geometric shapes. The thorough discussion of solutions and interactive questions promotes a deeper understanding and real-world application of the concepts learned.

Diskusi Concepts

1. 📝 Question 1: If a square with a side of 4 cm is enlarged by a scale factor of 3, what will be the new area and perimeter? 2. ➡️ Solution: 3. To find the new sides, simply multiply the original side by the scale factor: 4 cm * 3 = 12 cm. 4. The new area is calculated by squaring the new side: 12 cm * 12 cm = 144 cm². 5. The new perimeter is found by adding all the sides: 12 cm * 4 = 48 cm. 6. 📝 Question 2: A rectangle measures 6 cm and 8 cm. If reduced by a scale factor of 0.5, what will be the new area and perimeter? 7. ➡️ Solution: 8. To calculate the new sides, multiply each side by the scale factor: 6 cm * 0.5 = 3 cm and 8 cm * 0.5 = 4 cm. 9. The new area is calculated by multiplying the new sides: 3 cm * 4 cm = 12 cm². 10. The new perimeter is found by adding all the sides: (3 cm + 4 cm) * 2 = 14 cm. 11. 📝 Question 3: A triangular shape has sides of 5 cm each. If these sides are enlarged by a scale factor of 2, what will the new perimeter be? 12. ➡️ Solution: 13. To find the new sides, multiply each side by the scale factor: 5 cm * 2 = 10 cm. 14. The new perimeter is found by adding all the sides: 10 cm + 10 cm + 10 cm = 30 cm.

Engaging Students

1. 🔍 Question 1: Why does the area of a shape increase faster than the perimeter when the sides are enlarged? 2. 🔍 Question 2: How would you use the concept of proportionality to tackle everyday problems, like adjusting a recipe? 3. 🔍 Question 3: If a scale factor is a fraction less than 1, what does it signify about the resulting shape? 4. 🔍 Question 4: Why is understanding scales and proportionality important in fields such as engineering and architecture?

Conclusion

Duration: (10 - 15 minutes)

This stage aims to recap and reinforce the central concepts discussed throughout the lesson, solidifying students' understanding of enlargement and reduction of geometric shapes. It also underscores the practical applications and significance of these concepts, preparing students to utilize this knowledge in various real-life scenarios.

Summary

['Understanding proportionality and its role in the enlargement and reduction of geometric shapes.', 'How to calculate the new area and perimeter of enlarged and reduced shapes.', 'Solving practical problems involving the enlargement and reduction of geometric shapes.']

Connection

Throughout the lesson, theory was brought to life with practical examples that demonstrated how to calculate the new areas and perimeters of geometric shapes post enlargement or reduction. This enabled students to see how theoretical concepts translate to real-life situations, such as creating and modifying architectural models.

Theme Relevance

Comprehending how enlargement and reduction of geometric shapes affect their areas and perimeters is crucial for various daily and professional applications. This knowledge is particularly valuable in fields like architecture, engineering, and even in tailoring and crafts, where working with scales and proportions is routine.