Lesson Plan | Traditional Methodology | Addition and Subtraction of Decimal Numbers

Objectives

Duration: (10 - 15 minutes)

This stage aims to clearly present the objectives of the lesson, establishing what is expected of students to learn by the end of the session. By defining the objectives, students will have a clear understanding of what will be addressed and what the focus of learning will be, facilitating the assimilation of content and the application of skills developed during the lesson.

Main Objectives

1. Recognize the properties of addition and subtraction of decimal numbers.

2. Solve problems involving the addition and subtraction of decimal numbers using algorithms.

Introduction

Duration: (10 - 15 minutes)

The purpose of this stage of the lesson plan is to create a relevant context for students, demonstrating the practical importance of learning to deal with decimal numbers. The introduction also aims to spark students' interest in the topic, showing how mathematics is present in daily life and is useful in various situations.

Context

To start the lesson on the addition and subtraction of decimal numbers, begin by explaining to students that decimal numbers are used in daily life, such as in shopping situations, where we need to calculate prices, change, and discounts. Explain that understanding how to add and subtract decimal numbers is essential for dealing with money, measuring quantities in cooking recipes, and interpreting data in graphs and tables.

Curiosities

Did you know that the prices of products in stores are usually expressed in decimal numbers? For example, a chocolate bar might cost R$ 3.50. The ability to add and subtract these values helps not only in making purchases but also in calculating whether the money we have is enough to pay for the items we want.

Development

Duration: (40 - 50 minutes)

The purpose of this stage of the lesson plan is to deepen students' knowledge about the addition and subtraction of decimal numbers. Through detailed explanations, practical examples, and guided problem-solving, students will be able to clearly understand the techniques necessary to perform these operations accurately. Additionally, practice with questions will allow students to apply what they have learned and reinforce their understanding of the topic.

Covered Topics

1. Introduction to Decimal Numbers: Explain that decimal numbers are an extension of whole numbers, used to represent values that are between whole numbers. Detail the position of the decimal point and how it separates the whole part from the decimal part. 2. Alignment of Decimal Numbers: Address the importance of correctly aligning decimal numbers by the decimal point when performing addition and subtraction operations. Use visual examples to illustrate. 3. Addition of Decimal Numbers: Demonstrate how to add decimal numbers, starting with aligning the numbers and proceeding with the addition column by column, from right to left. Provide detailed examples, such as 3.45 + 1.76. 4. Subtraction of Decimal Numbers: Explain the subtraction of decimal numbers in a manner similar to addition, highlighting the need to align the numbers and subtract column by column. Use examples, such as 5.83 - 2.47. 5. Problem Solving: Present practical problems that require the addition and subtraction of decimal numbers, contextualizing them in everyday situations like shopping and measurements. Solve the problems step by step.

Classroom Questions

1. Calculate the sum of 4.32 and 7.58. 2. Subtract 9.47 from 15.62. 3. If you have R$ 20.00 and buy a book that costs R$ 12.75, how much change will you get?

Questions Discussion

Duration: (20 - 25 minutes)

🔍 Purpose: This stage of the lesson plan aims to consolidate students' understanding of the addition and subtraction of decimal numbers. Through detailed discussion of the solutions and engagement with reflective questions, students have the opportunity to review concepts, clarify doubts, and share different approaches to solving the problems, thereby strengthening both collective and individual understanding of the content.

Discussion

• 📝 Discussion of Resolved Questions:

• To calculate the sum of 4.32 and 7.58, the numbers must be aligned by the decimal point:

  4.32
+ 7.58
-------
 11.90

First, we add the decimal places from right to left. Adding 2 and 8 gives us 10. We write down 0 and carry over 1. Then, we add 3 and 5, plus the 1 we carried over, resulting in 9. In the unit's place, we add 4 and 7, plus 1, resulting in 12. Therefore, the sum is 11.90.

• To subtract 9.47 from 15.62, we align the numbers by the decimal point:

 15.62
- 9.47
-------
  6.15

We subtract the decimal places from right to left. First, we subtract 7 from 2, needing to borrow 1 from the next place, turning 2 into 12 and 6 into 5, resulting in 5. We subtract 4 from 5, resulting in 1. In the unit's place, we subtract 9 from 15, resulting in 6. Therefore, the subtraction is 6.15.

• To calculate the change when buying a book for R$ 12.75 with a R$ 20.00 bill, we align the numbers:

 20.00
-12.75
-------
  7.25

We subtract the decimal places from right to left. We subtract 5 from 0, borrowing 1 from the next place, turning 0 into 10 and the next 0 into 9, resulting in 5. We subtract 7 from 9, resulting in 2. In the unit's place, we subtract 2 from 9, resulting in 7. Therefore, the change is R$ 7.25.

Student Engagement

1. 🤔 Student Engagement: 2. What was the most difficult part of adding or subtracting decimal numbers? Why? 3. How did you feel when solving the practical problems? Did you feel confident? 4. Were you able to identify where you needed to correctly align the decimal numbers? What was the importance of that? 5. In what other daily situations do you think you will use the addition and subtraction of decimal numbers? 6. Did anyone have a different strategy for solving the problems? If yes, what was it?

Conclusion

Duration: (10 - 15 minutes)

The purpose of this stage of the lesson plan is to summarize the main content presented, reinforce the connection between theory and practice, and highlight the importance of the topic for students' daily lives. This helps consolidate learning and motivates students to apply the concepts in real situations, ensuring a deeper and more lasting understanding of the content.

Summary

• Decimal numbers are an extension of whole numbers, used to represent values between whole numbers.
• The importance of correctly aligning decimal numbers by the decimal point when performing addition and subtraction operations.
• How to add decimal numbers by aligning the numbers and adding column by column, from right to left.
• How to subtract decimal numbers by aligning the numbers and subtracting column by column, from right to left.
• Solving practical problems involving the addition and subtraction of decimal numbers in everyday situations.

The lesson connected theory with practice by presenting concepts of addition and subtraction of decimal numbers, followed by practical examples and problem-solving in daily situations, such as shopping and measurements. This allowed students to see the direct application of mathematical concepts in real situations, facilitating understanding and relevance of the topic.

Understanding the addition and subtraction of decimal numbers is fundamental for daily life, as these operations are used in various practical situations, such as shopping, calculating change, measuring ingredients in recipes, and interpreting data in graphs and tables. Being able to handle decimal numbers makes daily activities more precise and efficient.