NGSS Task: Macroscopic Energy vs. Microscopic Particles

Estimated Time: 45 minutes Materials: Device with internet access, simulation link, laboratory notebook.

Part 1: Engage (Anchoring Phenomenon)

Phenomenon: When you stretch a rubber band, it feels warm when it snaps back. When water boils, bubbles of gas form rapidly and it’s too hot to touch. How are these large-scale changes related to what happens to the tiny, invisible particles inside?

Think about these everyday examples and consider: How can we explain these large, visible (macroscopic) energy changes in terms of the tiny, invisible (microscopic) particles that make up the materials?

Student Questions:

1. Generate two questions you “need to know” about how the temperature or stretching of a material relates to its internal particles.

Part 2: Explore (Simulation Investigation)

Open the Macroscopic Energy vs. Microscopic Particles simulation. You will collect data on both thermal and potential energy.

Investigation A: Thermal Energy

1. Make sure you are on the Thermal Energy tab.
2. Observe the initial state of the particles in the microscopic view at a low macroscopic temperature.
3. Use the temperature slider (temp-slider) to increase the temperature.

4. Click “Record Data Point” at five different temperature values (e.g., 20 °C, 40 °C, 60 °C, 80 °C, 100 °C).

5. Record your data in the table below:

Investigation B: Potential Energy

1. Switch to the Potential Energy tab.
2. Observe the molecular bonds.
3. Use the stretch slider (stretch-slider) to increase the stretching of the bonds.

4. Click “Record Data Point” at five different stretch percentages (e.g., 0%, 25%, 50%, 75%, 100%).

5. Record your data in the table below:

Part 3: Explain (Sensemaking)

Using the data you collected, answer the following questions:

1. Thermal Energy: Describe the relationship between the macroscopic temperature of the system and the microscopic kinetic energy (motion/vibration) of the particles. Cite specific data points from Investigation A.
2. Potential Energy: Describe the relationship between the macroscopic stretching of the material and the microscopic potential energy (energy associated with relative positions of particles). Cite specific data points from Investigation B.
3. How does the macroscopic manifestation of thermal energy differ from potential energy when looking at the microscopic scale?

Part 4: Elaborate / Evaluate (Argumentation & Modeling)

Scientific Explanation: Construct a scientific explanation to support the claim: Energy at the macroscopic scale can be accounted for as a combination of energy associated with the motions of particles and energy associated with the relative position of particles.

Your explanation must include:

• Claim: A statement answering the prompt based on your data.
• Evidence: Specific references to the data tables from both Investigation A and Investigation B, as well as observations of the particle models.
• Reasoning: Use the concepts of kinetic energy and potential energy at the microscopic level to explain the macroscopic properties of temperature and stretching. Show how the model illustrates these relationships.

Part 5: Extension Options

• Mathematical Modeling: Create a line graph comparing the macroscopic variable (temperature or stretch) on the x-axis to the microscopic variable (kinetic or potential energy) on the y-axis. Determine if the relationship is linear or exponential.
• Phase Change Connection: Research how adding thermal energy beyond the boiling point affects the potential energy (rather than kinetic energy) of the particles as they transition from liquid to gas.

Teacher Notes & Alignment

• Target Performance Expectation: HS-PS3-2 (Develop and use models to illustrate that energy at the macroscopic scale can be accounted for as a combination of energy associated with the motions of particles (objects) and energy associated with the relative position of particles (objects).)
• Science and Engineering Practice: Developing and Using Models (Develop and use a model based on evidence to illustrate the relationships between systems or between components of a system).
• Disciplinary Core Idea: PS3.A: Definitions of Energy (These relationships are better understood at the microscopic scale, at which all of the different manifestations of energy can be modeled as a combination of energy associated with the motion of particles and energy associated with the configuration/relative position of the particles).
• Crosscutting Concept: Energy and Matter (Energy cannot be created or destroyed; it only moves between one place and another place, between objects and/or fields, or between systems).
• Evidence of Student Understanding: Students will use the simulation (a computational model) to describe and map relationships between macroscopic variables (temperature, stretch) and microscopic phenomena (particle motion, relative particle position). Their final explanation will directly address the Evidence Statements by depicting forms of energy at two different scales (macroscopic vs. molecular/atomic) and describing how thermal energy relates to kinetic energy of particles, and how relative position relates to potential energy.