Lesson Plan
Energy on the Edge: What is Potential?
Students will be able to define potential energy and provide examples of both gravitational and elastic potential energy to explain how energy can be stored.
Understanding potential energy helps students grasp how energy is stored and released in everyday life, from a stretched rubber band to an object held high, laying the groundwork for more complex physics concepts.
Audience
7th Grade Students
Time
45 minutes
Approach
Through direct instruction, interactive slides, and a hands-on lab activity.
Materials
- Stored Energy Slides, - Stretching and Compressing Lab, - Rubber bands, - Small weights or objects that can be dropped (e.g., erasers, small toys), - Rulers, and - Spring scales (optional)
Prep
Preparation Steps
15 minutes
- Review the Stored Energy Slides and practice the presentation.
- Print copies of the Stretching and Compressing Lab worksheet for each student or group.
- Gather materials for the lab: rubber bands, small weights/objects, rulers (and optional spring scales).
- Arrange desks for group work for the lab activity.
- Review all generated materials as needed.
Step 1
Engage & Inquire: What Makes a Roller Coaster Thrilling?
5 minutes
- Begin by asking students: 'Imagine a roller coaster. When is it most exciting? When it's at the very top of a huge drop, or speeding along the ground? Why do you think that is?'
- Introduce the concept of stored energy without naming it directly. 'Today, we're going to explore what gives things the 'potential' to do something exciting, like a roller coaster about to drop!'
- Display the first slide of the Stored Energy Slides.
Step 2
Explore & Discover: Stored Energy Demo
10 minutes
- Show students a rubber band. 'What happens if I stretch this rubber band and then let it go?' (It flies). 'What about if I hold this weight up high and then drop it?' (It falls).
- Explain that in both cases, energy was stored, giving the objects the 'potential' to move or do work.
- Introduce the term 'Potential Energy' using Stored Energy Slides. Explain that it's stored energy due to an object's position or state.
- Briefly introduce the two types for today: Gravitational Potential Energy (height) and Elastic Potential Energy (stretching/compressing).
Step 3
Explain & Define: Deep Dive into Potential Energy
15 minutes
- Use the Stored Energy Slides to explain Gravitational Potential Energy. Provide clear examples like a book on a shelf, water behind a dam, or a skier at the top of a mountain.
- Discuss how mass and height affect gravitational potential energy. 'Which has more potential energy: a feather held high or a bowling ball held high?'
- Transition to Elastic Potential Energy using the slides. Explain it as energy stored in elastic materials when they are stretched or compressed. Examples: a stretched rubber band, a compressed spring, a pulled back bowstring.
- Discuss how much an object is stretched or compressed affects elastic potential energy. 'Which has more potential energy: a slightly stretched rubber band or a very stretched rubber band?'
Step 4
Apply & Extend: Stretching and Compressing Lab
15 minutes
- Distribute the Stretching and Compressing Lab worksheet and the lab materials (rubber bands, weights, rulers).
- Explain the instructions for the lab activity. Students will experiment with stretching rubber bands and lifting objects to observe and record how potential energy changes.
- Circulate among groups to answer questions and facilitate observations.
- Conclude by asking students to share their observations and discuss how their experiments demonstrated gravitational and elastic potential energy.
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Slide Deck
Energy on the Edge: What is Potential?
What makes a roller coaster exciting before the big drop?
Think about:
- The feeling at the top
- What's about to happen!
Greet students and start with the roller coaster hook question. Encourage initial thoughts and predictions. This sets the stage for thinking about stored energy.
Energy in Waiting
Imagine:
- A stretched rubber band
- A book held high
What do they have in common? They're both ready to move or do something!
Perform the simple demo with the rubber band and the raised object. Ask students what they observe. Guide them to think about what these objects 'have' that allows them to move.
What is Potential Energy?
Potential Energy (PE)
- Stored energy an object has because of its position or state.
- It has the potential to do work or cause motion.
- It's like a battery charged up and ready to go!
Introduce the formal definition of Potential Energy. Emphasize 'stored energy' and 'position or state.' Connect it back to the previous examples.
Gravitational Potential Energy (GPE)
Energy stored due to an object's height above the ground.
Think about:
- A rock on a cliff
- Water behind a dam
- A diver on a high board
The higher the object and the more massive it is, the more GPE it has!
Focus on Gravitational Potential Energy. Explain how height and mass contribute. Use the examples provided and ask students for their own examples.
Elastic Potential Energy (EPE)
Energy stored in elastic materials when they are stretched or compressed.
Think about:
- A stretched rubber band
- A compressed spring
- A pulled-back slingshot
The more an object is stretched or compressed, the more EPE it has!
Focus on Elastic Potential Energy. Explain how stretching or compressing elastic materials stores energy. Use the examples provided and ask students for their own.
GPE vs. EPE: Can You Tell the Difference?
Which type of potential energy is at play?
- A car parked at the top of a hill.
- A coiled toy snake in a can.
- A trampoline with someone jumping on it.
- A pendulum at the highest point of its swing.
Briefly recap both types. Ask students to differentiate between GPE and EPE based on the examples. Prepare them for the lab activity.
Stretching and Compressing Lab
Let's explore potential energy with some hands-on experiments!
Today, you will:
- Investigate how stretching and compressing changes energy.
- Observe how height affects energy.
- Record your findings!
Introduce the lab activity. Explain that they will be exploring both types of potential energy hands-on. Emphasize safety and following instructions.
Potential Power!
Key Takeaways:
- Potential energy is stored energy.
- Gravitational Potential Energy comes from height.
- Elastic Potential Energy comes from stretching or compressing.
Now you know what gives things the 'potential' to move!
Conclude the lesson by reviewing the main concepts. Ask students to summarize what potential energy is and give an example of each type.
Activity
Stretching and Compressing Lab: Exploring Potential Energy
Objective
To observe and understand how potential energy is stored in objects due to their height (gravitational potential energy) and their deformation (elastic potential energy).
Materials (per group)
- 1-2 Rubber bands
- 1 Small weight or object that can be dropped (e.g., eraser, small toy)
- 1 Ruler
Part 1: Gravitational Potential Energy
Instructions:
- Hold the small weight/object at different heights above your desk (e.g., 5 cm, 10 cm, 20 cm, 30 cm).
- Carefully drop the object from each height and observe what happens when it hits the desk or floor.
- Record your observations in the table below.
Observations:
| Height (cm) | Observation (How much impact did it have? How fast did it go?) |
|---|---|
| 5 | |
| 10 | |
| 20 | |
| 30 |
Reflection Questions:
- What did you notice about the impact of the object as the height increased?
- How does the height of an object relate to its gravitational potential energy?
Part 2: Elastic Potential Energy
Instructions:
- Take a rubber band and stretch it a small amount (e.g., 2 cm).
- Hold it stretched and then release one end, letting it snap back. Observe the snap.
- Now, stretch the rubber band a larger amount (e.g., 5 cm, 10 cm).
- Release it again and observe the snap.
- Record your observations in the table below.
Observations:
| Stretch Distance (cm) | Observation (How strong was the snap? How far did it go?) |
|---|---|
| 2 | |
| 5 | |
| 10 |
Reflection Questions:
- What did you notice about the strength of the snap as you stretched the rubber band further?
- How does the amount of stretch or compression in an elastic object relate to its elastic potential energy?
Conclusion
In your own words, explain the difference between gravitational potential energy and elastic potential energy, providing one new example for each.