Objectives (5 - 7 minutes)

1. Understand the concept of resistors in parallel: The main objective is for students to understand what resistors in parallel are, why they are used, and how they affect the current flow in a circuit.

2. Calculate the total resistance in a circuit with resistors in parallel: Students should be able to apply the correct formula to calculate the total resistance in a circuit that includes resistors in parallel. This will involve the use of mathematical concepts, such as inverses and sum of resistances.

3. Solve practical problems involving resistors in parallel: In addition to understanding the concept and the formula, students should also be able to apply their knowledge to solve practical problems. This may involve determining the total resistance, the current in each resistor, or the voltage across each resistor.

Secondary Objectives:

• Compare and contrast resistors in series and in parallel: Students should also be able to differentiate between resistors in series and in parallel, understanding how they affect the current flow and the total resistance of a circuit.

• Apply the concept of resistors in parallel in real-world situations: Students should be able to identify examples of resistors in parallel in the world around them and understand how these circuits work.

Introduction (10 - 15 minutes)

1. Review of previous concepts (3 - 5 minutes): The teacher starts the lesson by briefly reviewing the concepts of electric current, resistance, and resistors in series, as these are fundamental to understanding the new topic of resistors in parallel. This may involve quick questions to the students to check if they remember these concepts.

2. Problem situations (5 - 7 minutes): To engage students, the teacher can present two problem situations related to the lesson topic:

   • Situation 1: "Imagine you have a set of identical light bulbs, each with a resistance of 5 ohms. If you connect them in series, what will happen to the brightness of the light bulbs? And if you connect them in parallel?"

   • Situation 2: "Now, suppose you have a circuit with three identical resistors. Two are connected in series and this set is connected in parallel with the third resistor. How would you calculate the total resistance of this circuit?"

3. Topic contextualization (2 - 3 minutes): The teacher should then explain the importance of the topic, showing practical examples of where resistors in parallel are used in everyday life. This may include examples of circuits at home, school, work, industry, and in electronic devices.

4. Introduction to the topic (2 - 3 minutes): Finally, the teacher introduces the topic of resistors in parallel, explaining that this is a fundamental concept in the study of electricity and is widely used in practical applications. The teacher can then share two curiosities or interesting facts about the topic:

   • Fact 1: "Did you know that most electrical circuits at home and in most electronic devices use a combination of resistors in series and in parallel to control current and voltage?"

   • Fact 2: "Interestingly, when you add resistors in parallel to a circuit, the total resistance of the circuit decreases. This is opposite to what happens when you add resistors in series, where the total resistance increases."

Development (20 - 25 minutes)

1. Theory (10 - 12 minutes): The teacher should start the lesson by explaining the theory behind resistors in parallel. This may include:

   • Definition of Resistors in Parallel (2 - 3 minutes): The teacher should explain that resistors in parallel are those that are connected in such a way that the electric current is divided between them. That is, the current that enters one resistor is divided among all resistors in parallel.

   • Effect on Total Resistance (2 - 3 minutes): The teacher should explain that by adding resistors in parallel to a circuit, the total resistance of the circuit decreases. This occurs because, with more paths for the current to flow, the total resistance is divided among the resistors.

   • Equation for Resistors in Parallel (2 - 3 minutes): The teacher should introduce the formula to calculate the total resistance in a circuit with resistors in parallel. The formula is: 1/Rt = 1/R1 + 1/R2 + ... + 1/Rn, where Rt is the total resistance and R1, R2, ..., Rn are the resistances of the resistors in parallel.

   • Examples of Applications (2 - 3 minutes): The teacher should give examples of where resistors in parallel are used in practice. This may include circuits at home, in industry, in electronic devices, etc.

2. Resolution of Examples (10 - 13 minutes): After explaining the theory, the teacher should move on to solving practical examples. This may include:

   • Example 1 (3 - 4 minutes): The teacher can start with a simple example, such as a circuit with two 5-ohm resistors in parallel. Students should be guided step by step through the resolution of the example, including the application of the formula to calculate the total resistance.

   • Example 2 (3 - 4 minutes): The teacher can then move on to a more complex example, such as a circuit with three or more resistors of different values in parallel. Students should be guided through the resolution of the example, including simplifying fractions and solving equations to find the total resistance.

   • Practical Exercise (4 - 5 minutes): Finally, the teacher should give students the chance to solve a problem on their own. This may be a problem similar to the solved examples, or it may be a slightly more challenging problem. The teacher should circulate around the room, offering help and feedback as needed.

3. Discussion (2 - 3 minutes): After solving the examples and the practical exercise, the teacher should allow time for discussion. Students should be encouraged to ask questions, share their strategies for solving problems, and discuss the practical applications of what they have learned. The teacher should facilitate the discussion, ensuring that all students have the opportunity to speak and that the conversation remains focused on the lesson topic.

Return (5 - 7 minutes)

1. Lesson Review (2 - 3 minutes): The teacher should review the main points covered in the lesson. This may include a summary of the concept of resistors in parallel, the formula for calculating the total resistance, and examples of how to apply this knowledge to solve practical problems. The teacher can use a circuit diagram with resistors in parallel to reinforce the concept.

2. Connection to Practice (2 - 3 minutes): Next, the teacher should explain how the theory connects to practice. This may involve reviewing the practical examples used during the lesson and discussing how these examples can be applied in real-world situations. For example, the teacher may recall the situation of the identical light bulbs from the beginning of the lesson and explain how connecting them in parallel reduces the total resistance, resulting in brighter light bulbs.

3. Individual Reflection (1 - 2 minutes): The teacher should then ask students to think for a minute about what they learned in the lesson. They should reflect on the following questions:

   1. What was the most important concept you learned today?
   2. What questions do you still have about resistors in parallel?

4. Student Feedback (1 - 2 minutes): Finally, the teacher should ask students to share their answers with the class. This can be done through a group discussion or a brief written response. Student feedback can be used to inform the planning of future lessons and to identify any areas of confusion that need to be addressed again.

This Return is crucial to consolidate students' learning, allow them to reflect on what they have learned, and identify any areas of confusion. Additionally, by requesting feedback from students, the teacher demonstrates that they value their opinions and are willing to adapt their teaching to meet individual learning needs.

Conclusion (5 - 7 minutes)

1. Recapitulation (2 - 3 minutes): The teacher should start the Conclusion by summarizing the main points covered during the lesson. This includes the definition of resistors in parallel, how they affect the total resistance of a circuit, the formula for calculating the total resistance, and examples of how to apply this knowledge to solve practical problems. The teacher can do this interactively by asking students to share what they remember about these points.

2. Connection between Theory, Practice, and Applications (1 - 2 minutes): Next, the teacher should emphasize how the lesson connected the theory of resistors in parallel with practice and real-world applications. This may include reviewing the practical examples used during the lesson and discussing how these examples apply to real situations. For example, the teacher may recall the situation of the identical light bulbs from the beginning of the lesson and explain how connecting them in parallel reduces the total resistance, resulting in brighter light bulbs.

3. Extra Materials (1 - 2 minutes): The teacher should then suggest extra materials for students who want to deepen their understanding of the topic. This may include recommended readings, explanatory videos, interactive websites, circuit simulation apps, etc. For example, the teacher may recommend a YouTube video that demonstrates the difference between a light bulb in series and in parallel, or an interactive website that allows students to experiment with different resistor configurations in a circuit.

4. Importance of the Topic (1 - 2 minutes): Finally, the teacher should explain the importance of the topic for students' daily lives. This may include discussing how resistors in parallel are used in a variety of applications, from home circuits to the electronic devices we use daily. The teacher may also highlight how understanding resistors in parallel can help students better understand the functioning of electricity in general.

The Conclusion is an important part of the lesson, as it helps consolidate students' learning, connect theory with practice and applications, and motivate students to continue learning about the topic.