Thermal Energy Diagnostics

Question 4: Toast on Plate Correct: B

Conservation of Energy: In a closed interaction, the thermal energy gained by the plate must come from the toast.

Misconception: Option A suggests heat transfers without any energy decrease in the heat source.

Question 5: Shuttle Carbon Layers (Equal System Equilibrium) Correct: A

Outer layer molecules (energy 90) collide with inner layer molecules (energy 50). Kinetic energy transfers strictly from higher to lower energy until thermal equilibrium is established.

Total E = (8 × 90) + (8 × 50) = 720 + 400 = 1120 Final Temp = 1120 ÷ 16 = 70.0 (intermediate)

Question 6: Louis's Machine Gears (System Mass & Particle Distribution) Correct: B

Both top gears supply identical energy transfers (4 molecules at 80). In Set B, that thermal energy spreads over 8 bottom molecules instead of 4, producing a lower final average temperature.

Set A Final: (320 + 160) ÷ 8 = 60.0 Set B Final: (320 + 320) ÷ 12 = 53.3 → Bottom Gear B is cooler!

Thermal Energy Assessment • Teacher Scoring Guide Page 1 of 2

Part 2 Rubrics

Constructed Response Rubrics & Diagnostic Matrix

Questions 7 & 8

Question 7: Chef's Stacking Dish Selection (2 Points)

Core Focus: Differentiating Average Kinetic Energy (Temperature) from Total Thermal Energy

Correct: Dish C

Scientific Rationale & Equilibrium Calculations:

• Dish A: 10 molecules × 30 = 300 total E. Combined with food dish: (300 + 40) ÷ 14 = 24.3 avg energy.
• Dish B: 10 molecules × 10 = 100 total E. Same temperature as food dish (10). No net heat transfer occurs.
• Dish C: 6 molecules × 50 = 300 total E. Combined with food dish: (300 + 40) ÷ 10 = 34.0 avg energy!

Even though Dish A and C start with the identical total energy (300), Dish C warms the food dish significantly more because its energy is concentrated into fewer molecules (higher initial temperature of 50).

2 Points (Proficient)

Selects Dish C. Explains that Dish C has higher average kinetic energy/temperature, and when energy transfers from hot dish to cooler food, it raises the food to a higher final temperature (less total molecules to share energy).

1 Point (Approaching)

Selects Dish C but explanation is incomplete (e.g., mentions it has 50 energy without explaining transfer mechanism or equilibrium), OR selects Dish A due to total energy misconception but provides logical reasoning.

0 Points (Novice)

Selects Dish B, guesses without explanation, or relies on intuitive misconceptions (e.g., "Dish A has the most molecules so it wins").

Question 8: Avanti's Bookstore Book Stacks (2 Points)

Core Focus: Predicting Equilibrium Outcomes Across Differing Molecular Densities

Correct: Top Book 2 Warmer

Scientific Rationale & Proof:

Before touching: Both top books have identical starting temperature (3.0); both bottom books have identical starting temperature (7.0). Bottom books are hotter.
After touching: In Stack 1, Bottom Book 1 transfers energy into 10 top molecules (Final temp = 58 ÷ 14 ≈ 4.14). In Stack 2, Bottom Book 2 transfers the same energy into only 4 top molecules (Final temp = 40 ÷ 8 = 5.0). Thus, Top Book 2 will be warmer.

2 Points (Proficient)

States temperatures were equal before touching (3 vs 3). Correctly identifies Top Book 2 will be warmer after touching because energy from the bottom book is concentrated across fewer molecules.

1 Point (Approaching)

Correctly compares initial temperatures but makes an error in final temperature comparison, OR correctly states Top Book 2 is warmer but provides incomplete reasoning.

0 Points (Novice)

Incorrectly states Top Book 1 is warmer (confusing total molecules with higher temperature) or provides irrelevant justification.

Pre-Unit Diagnostic Misconception Guide (How to Use Student Data)

1. Caloric / Particle Model of Heat: Students who pick Q1(a) or Q3(d) view heat as a fluid or particle rather than molecular motion. Plan targeted demonstrations with the particle simulator.

2. "Cold" as an Active Agent: Students picking Q1(d), Q3(c), Q4(d), or Q5(d) think cold flows into objects. Emphasize that "cooling" is always the departure of kinetic energy.

3. Equilibrium = Highest Temp: Students picking Q5(b) believe warmer objects heat cooler ones until both hit the highest starting temperature. Emphasize energy conservation and averaging.

4. Confusing Total Energy & Temp: Students picking Dish A in Q7 confuse mass/total energy with temperature (concentration of kinetic energy). Use gear and dish examples during instruction.

Thermal Energy Assessment • Teacher Scoring Guide Page 2 of 2