Learning Objectives (5-7 minutes)

1. Understand the concept of simple interest and its application in a financial context.

   • Identify the difference between the principal, interest rate, and time, and how they affect the calculation of simple interest.
   • Calculate the interest and the total amount in problem situations that involve simple interest.

2. Develop the ability to solve practical problems involving simple interest.

   • Apply the theoretical knowledge acquired to solve simple interest problems, both in hypothetical and real situations.

3. Apply simple interest in everyday situations.

   • Identify everyday situations that involve simple interest and apply the acquired knowledge to solve these problems.
   • Develop a practical understanding of how simple interest affects personal and business finances.

Secondary objectives:

1. Develop critical thinking and problem-solving skills by applying mathematical concepts in real-world situations.

2. Encourage active student participation through practical and interactive learning activities.

Introduction (10-15 minutes)

1. The teacher begins the class by reviewing the basic concepts of percentage and proportionality, as they are fundamental to understanding simple interest. This can be done through a short quiz or classroom discussion to check students' prior knowledge and clarify any doubts that may exist. (3-5 minutes)

2. The teacher then proposes two problem situations to pique students' interest:

   • Situation 1: Imagine that a friend asks you to borrow $100 for a month and promises to pay back $105 at the end. How would you calculate the simple interest rate in this case?

   • Situation 2: Suppose you are planning to save up to buy a new cell phone that costs $1,000. The seller offers you the option of paying in two months without interest or in three months with 10% interest. What would be the best financial option? (5-7 minutes)

3. The teacher contextualizes the importance of simple interest in everyday life, highlighting situations such as personal loans, financing, fixed-income investments, among others. He explains that understanding and being able to calculate simple interest can help make more informed and effective decisions regarding personal finances. (2-3 minutes)

4. To gain students' attention, the teacher shares some curiosities or practical applications of simple interest:

   • Curiosity 1: The concept of simple interest is one of the oldest in financial mathematics, dating back more than 4,000 years, when it was used by ancient civilizations such as the Egyptians and Babylonians.

   • Curiosity 2: Simple interest can be used to calculate the time it will take to double an investment. For example, if you invest $1,000 at an interest rate of 5% per year, it will take approximately 14.2 years for your investment to double. This is known as the "rule of 72" and is widely used in the world of finance. (3-5 minutes)

Development (20-25 minutes)

1. Role-play Activity: The teacher suggests that students divide into groups of five. Each group will represent a different situation involving simple interest. The situations could be: a personal loan, financing a consumer good, a financial investment, an interest-free installment purchase, and an installment purchase with interest. The teacher provides cards with the values involved in each situation and the interest rates. Students need to calculate the interest and the final amount in each situation. At the end of the activity, each group presents its situation and the calculations performed to the class. (10-12 minutes)

   • Step 1: The teacher divides the class into groups and distributes cards with the situations to each group.
   • Step 2: Students discuss the situation, identify the relevant values (principal, rate, and time), and calculate the interest and the final amount.
   • Step 3: Each group presents its situation and the calculations made to the class.

2. Practical Activity: The teacher proposes a practical activity for the students, in which they will have to calculate the interest and the final amount of a real situation. To do this, the teacher brings different advertisements from stores that offer installment sales with interest. The teacher asks students to choose an advertisement, identify the relevant values (cash price, number of installments, and interest rate), and calculate the interest and the final amount. Then, students discuss the financial implications of this purchase. (10-12 minutes)

   • Step 1: The teacher distributes the store advertisements to the students.
   • Step 2: Students choose an advertisement, identify the relevant values, and perform the calculations.
   • Step 3: Students discuss the financial implications of this purchase, considering the amount of interest and the final amount.

3. Group Discussion: To conclude the Development stage, the teacher leads a group discussion about the solutions found by each group. The teacher encourages students to share their conclusions and reflect on the importance of calculating simple interest for making financial decisions. (5-8 minutes)

   • Step 1: The teacher begins the discussion by highlighting the main conclusions and difficulties encountered by the groups.
   • Step 2: Students are encouraged to share their insights and reflect on the importance of calculating simple interest for everyday life.
   • Step 3: The teacher concludes the discussion by reinforcing the main points covered and connecting them to the theoretical content presented.

Review (8-10 minutes)

1. Group Review: The teacher begins the Review stage by asking each group to share with the class their solutions or conclusions found during the role-play and practice activities. Each group will have a maximum of 3 minutes to present. The teacher can ask questions to stimulate discussion and ensure that all key points are covered. (3-4 minutes)

   • Step 1: The teacher asks the first group to present their conclusions.
   • Step 2: The teacher asks relevant questions and stimulates discussion.
   • Step 3: The process is repeated with the other groups until all have had the opportunity to present.

2. Connection to Theory: After all presentations, the teacher makes the connection between the practical activities and the theory presented at the beginning of the class. He reinforces the concepts of simple interest, reviews the steps for the calculation, and highlights how these concepts were applied in the activities. The teacher also clarifies any doubts that may have arisen during the presentations. (2-3 minutes)

   • Step 1: The teacher recaptures the theory of simple interest.
   • Step 2: The teacher connects the theory with the practical activities, highlighting how the concepts were applied.
   • Step 3: The teacher clarifies doubts and reinforces the importance of calculating simple interest in everyday life.

3. Individual Reflection: The teacher suggests that students take a minute to reflect silently on what they learned during the class. He asks the following questions to guide the reflection:

   1. What was the most important concept you learned today?
   2. What questions have not yet been answered?

The teacher asks students to write down their answers, as they will be useful for the next class. (2-3 minutes)

- **Step 1**: The teacher proposes the reflection questions.
- **Step 2**: Students reflect silently and write down their answers.
- **Step 3**: The teacher concludes the Review stage and reinforces that the answers will be useful for the next class.

4. Feedback and Closing: To conclude the class, the teacher asks students for feedback on the class. He can ask questions like: "What was the most useful aspect of the class?" and "What could be improved?" The teacher thanks everyone for their participation and ends the class, reinforcing the topic of the next class and encouraging students to continue studying the content. (1-2 minutes)

- **Step 1**: The teacher asks students for feedback.
- **Step 2**: The teacher thanks everyone for their participation and ends the class.

Conclusion (5-7 minutes)

1. Content Summary: The teacher begins the Conclusion by recapping the main points of the class. He reinforces the concept of simple interest, explaining again the difference between the principal, interest rate, and time. The teacher also reviews the steps for calculating simple interest and how to apply it to find the amount. He can use diagrams or graphs to visualize these concepts. (2-3 minutes)

   • Step 1: The teacher recapitulates the main points of the class.
   • Step 2: The teacher reinforces the concept of simple interest, the steps for the calculation, and how to apply it.

2. Connection between Theory and Practice: The teacher then highlights how the class connected theory to practice. He mentions the role-play and practice activities, explaining how they helped students apply the concepts of simple interest in real situations. The teacher also reinforces the importance of understanding and being able to calculate simple interest to make informed financial decisions. (1-2 minutes)

   • Step 1: The teacher highlights the connection between theory and practice.
   • Step 2: The teacher reinforces the importance of calculating simple interest for making informed financial decisions.

3. Supplementary Materials: The teacher suggests additional materials for students who wish to deepen their knowledge of simple interest. He can recommend books, websites, videos, or apps that offer explanations and extra exercises on the subject. The teacher can also make some of these materials available on the school's learning platform. (1-2 minutes)

   • Step 1: The teacher suggests additional materials for self-study.
   • Step 2: The teacher makes the materials available on the school's learning platform.

4. Importance of the Subject: Finally, the teacher reinforces the importance of the subject for everyday life. He highlights how understanding and being able to calculate simple interest can help students make more informed financial decisions, whether in their personal finances or in future careers involving money management. The teacher also encourages students to continue practicing the calculation of simple interest in everyday situations. (1 minute)

   • Step 1: The teacher reinforces the importance of calculating simple interest for everyday life.
   • Step 2: The teacher encourages students to continue practicing the calculation of simple interest.