Objectives (5 - 7 minutes)

1. Students will understand the concept of Elastic Force and its relationship with the extension or compression of a spring or elastic material. They will be able to explain how elastic force works and its impact on the behavior of objects.

2. Students will be able to identify and differentiate between Hooke's Law and the concept of Elastic Limit. They will understand that Hooke's Law applies to elastic materials up to a certain point, beyond which the material becomes permanently deformed.

3. Students will develop the ability to apply their knowledge of Elastic Force to real-world situations. They will be able to analyze scenarios and predict the behavior of springs or elastic materials based on the forces acting upon them.

Secondary objectives:

• Students will enhance their problem-solving skills through hands-on activities and experiments related to Elastic Force.
• Students will improve their collaboration and communication skills as they work in groups during the practical activities.

Introduction (10 - 12 minutes)

1. The teacher begins the lesson by reminding students of the previous lessons on forces and motion, emphasizing the concepts of force, displacement, and equilibrium. This will provide the necessary background knowledge for understanding Elastic Force.

2. A problem situation is presented to the students: "Imagine you are a toy manufacturer, and you have designed a new toy that jumps up and down when you squeeze it. How does the toy work? What forces are at play here?" This problem situation will serve as a starting point for the introduction of Elastic Force.

3. The teacher then contextualizes the importance of Elastic Force by discussing its real-world applications. For instance, they can talk about how this force is used in various fields such as engineering (for designing springs in machines), sports (e.g., in pole vaulting and trampolining), and even in medical devices (e.g., in artificial limbs).

4. To grab the students' attention, the teacher presents a couple of interesting facts or stories related to Elastic Force. One story could be about Robert Hooke, the scientist who first described the concept of Elastic Force (Hooke's Law) in the 17th century. Another fact could be about how the world's tallest and fastest roller coasters rely on elastic forces to provide a thrilling ride.

5. The teacher then formally introduces the topic of Elastic Force, explaining that it is the force exerted by a compressed or extended spring or elastic material. They also introduce the terms "extension" (for a stretched material) and "compression" (for a compressed material), which are essential for understanding the topic.

6. The teacher concludes the introduction by stating the lesson's objectives and assuring the students that by the end of the lesson, they will not only understand Elastic Force but also be able to apply this knowledge to real-world situations. They also encourage the students to ask questions and participate actively in the lesson.

Development (20 - 25 minutes)

Activity 1: "Exploring Hooke's Law" (8 - 10 minutes)

1. The teacher divides the class into small groups and provides each group with a set of springs of different lengths and weights, a meter ruler, a weight hanger, and a set of known weights (e.g., 100g, 200g, 300g).

2. The groups are instructed to hang a spring from the ceiling and attach the weight hanger to the bottom of the spring. The students then measure the original length of the spring (when no weights are attached) using the meter ruler.

3. The students are then instructed to add different weights to the hanger and measure the new length of the spring each time. They record the data in a table.

4. After collecting the data, students plot a graph with the x-axis representing the added weight (force) and the y-axis representing the extension (change in length) of the spring. The teacher guides the students in interpreting and analyzing the graph.

5. The students should observe that the graph is a straight line passing through the origin, indicating a direct proportionality between the force applied (weight) and the extension of the spring. This observation leads to the discussion of Hooke's Law, F = kx, where F is the force applied, x is the extension, and k is the spring constant (a measure of the stiffness of the spring).

6. The teacher facilitates a class discussion on the limitations of Hooke's Law, introducing the concept of elastic limit (the maximum force a spring can handle before it doesn't return to its original shape).

Activity 2: "Elastic Force in Action" (10 - 12 minutes)

1. The teacher distributes to each group a toy that demonstrates elastic force, such as a Slinky, a bungee cord or a slingshot.

2. The students are tasked with examining the toy and identifying the forces at play when it is extended or compressed. They should also consider how the toy's design affects the strength and direction of the forces.

3. The teacher asks the students to draw a labeled diagram of their toy, identifying the forces and components responsible for its elasticity.

4. After drawing the diagram, the students are asked to explain their understanding of how the toy works in terms of Elastic Force. This includes discussing how the toy stores and releases energy.

5. The teacher walks around the room, providing support and clarifying any misconceptions. They also facilitate a class discussion where each group shares their toy, diagram, and explanation.

6. Lastly, the teacher highlights how the understanding of Elastic Force is crucial in various fields, such as engineering, where it's used to design springs, shock absorbers, and other devices.

Feedback (8 - 10 minutes)

1. The teacher initiates a group discussion where each group is asked to share their findings from the activities. They present the graphs they created in the first activity, explain their understanding of Hooke's Law, and describe how their toy represents Elastic Force. This exercise will help in assessing the students' understanding and application of the concept of Elastic Force. (3 - 4 minutes)

2. The teacher then encourages the students to reflect on the hands-on activities they performed and the concepts they learned during the lesson. The students are prompted to think about the following questions:

   • What was the most important concept you learned today about Elastic Force?
   • What questions do you still have about Elastic Force?
   • How can you apply the concept of Elastic Force in real-world situations?

3. The students are given a moment to reflect on these questions. They can either write down their thoughts or discuss them with their group. The teacher ensures that all students participate in this reflection process. (2 - 3 minutes)

4. After the reflection, the teacher invites a few students to share their responses with the class. This will provide insights into the students' understanding and help the teacher address any remaining misconceptions or questions. (2 minutes)

5. To conclude the lesson, the teacher summarizes the key points about Elastic Force and its application in real-world scenarios. They remind the students about the importance of Elastic Force in various fields, from engineering to sports. The teacher also assures the students that any remaining questions or doubts will be addressed in the next class. (1 minute)

6. Finally, the teacher assigns a small homework task. The students are asked to find one more real-world application of Elastic Force and prepare a short presentation on it for the next class. This assignment will further reinforce the students' understanding of the topic and encourage them to explore beyond the classroom. (1 minute)

Conclusion (5 - 7 minutes)

1. The teacher begins the conclusion by summarizing the main points covered in the lesson. They remind the students that Elastic Force is the force exerted by a compressed or extended spring or elastic material, and it is responsible for the behavior of objects that can stretch or compress. They reiterate the concept of Hooke's Law and the elastic limit. (1 - 2 minutes)

2. The teacher then explains how the hands-on activities and discussions helped the students understand and apply the concept of Elastic Force. They highlight how the first activity, "Exploring Hooke's Law," allowed students to observe the direct proportionality between the force applied and the extension of a spring, leading to the understanding of Hooke's Law. They also mention how the second activity, "Elastic Force in Action," allowed students to see the concept in real-world objects and situations, reinforcing their understanding. (1 - 2 minutes)

3. The teacher suggests additional materials for the students to further their understanding of Elastic Force. These materials could include videos demonstrating the concept of Elastic Force, virtual simulations allowing students to manipulate springs and observe their behavior, and reading assignments on the history and applications of Elastic Force. (1 minute)

4. The teacher then emphasizes the importance of Elastic Force in everyday life. They remind the students of the real-world applications discussed during the lesson, such as the design of springs in machines, the functioning of sports equipment like pole vaults and trampolines, and even medical devices like artificial limbs. They also encourage the students to be on the lookout for more examples of Elastic Force in their surroundings. (1 - 2 minutes)

5. Lastly, the teacher concludes the lesson by stating that understanding Elastic Force is not only crucial for their physics studies but also for understanding the world around them. They encourage the students to continue exploring the topic and to bring any further questions or observations to the next class. (1 minute)