Energy in Motion

Overview

Students investigate why a metal bench and wooden bench can feel different in sunlight, even when measured at the same temperature. They distinguish temperature from thermal energy, model heat transfer, and apply the first law of thermodynamics to data and a quantitative example. The lesson builds scientific reading, procedural accuracy, and evidence-based explanation.

Learning intentions

Students will be able to:

• Distinguish temperature, thermal energy, and internal energy using particle motion and amount of matter.
• Explain heat transfer by conduction, convection, and radiation.
• Follow a multistep investigation, record SI-unit data, and analyze results.
• Apply ΔU = Q − W, with clearly stated sign conventions.
• Summarize a technical explanation and support a conclusion with data from multiple sources.

Success criteria

• I can explain why two objects at the same temperature may have different thermal energies.
• I can identify and justify conduction, convection, and radiation in a real situation.
• I can calculate a change in internal energy using joules and state what the sign means.
• I can write a concise evidence-based conclusion from an investigation.

Curriculum links

• Reading technical texts: follow complex multistep procedures and analyze results using explanations in the text.
• Reading technical texts: determine central ideas, interpret domain-specific terms, and summarize accurately.
• Writing in science: conduct a short inquiry, synthesize data and text information, and write an informative explanation.
• Writing in science: organize complex ideas with headings, tables, equations, and evidence.

Lesson structure (60 minutes)

1. 0–7 min · Phenomenon and prediction. Open with the introduction and phenomenon slides showing a thermographic comparison of a metal and wooden bench in sunlight, then ask, “If both read 35 °C, which contains more thermal energy?” Students make an individual prediction, justify it in two sentences, and share with a partner. Teacher records competing ideas without confirming an answer.

2. 7–18 min · Direct instruction and vocabulary. Use the temperature, energy-transfer, and first-law slides to explain temperature as average kinetic energy per particle, while thermal energy is energy associated with the total microscopic motion and interactions of all particles; internal energy is the system’s total microscopic kinetic and potential energy. Define heat, Q, as energy transferred because of a temperature difference. Students complete the first section of the thermodynamics notes and investigation worksheet and answer two checks: “Can a large object at lower temperature contain more thermal energy?” and “Which transfer can occur through empty space?”

3. 18–28 min · First law and worked example. Model the convention ΔU = Q − W: Q is positive when energy enters the system as heat and negative when it leaves; W is positive when the system does work on its surroundings and negative when the surroundings do work on the system. Work through: a gas receives 600 J of heat and does 250 J of work, so ΔU = 600 J − 250 J = +350 J. Students solve a second case on the worksheet: 400 J enters as heat while 150 J of work is done on the gas, giving W = −150 J and ΔU = +550 J. Ask students to explain the sign, not only calculate.

4. 28–43 min · Hands-on data investigation. In groups of three, assign roles of equipment manager, timer/recorder, and evidence checker. Students use a lamp or sunny window, two equal-sized samples such as metal and wood, and thermometers: (a) measure initial temperatures; (b) expose both samples to the same radiant source for five minutes; (c) record temperature every minute; (d) move them to a room-temperature surface; and (e) record one additional cooling measurement. Students follow the numbered procedure on the investigation data table and analysis questions and identify where radiation, conduction, and convection occur. Safety: use a low-temperature lamp, keep materials away from flames, do not touch hot equipment, secure cords, and wash hands after handling materials. If equipment is limited, groups analyze the teacher’s prepared data set instead.

5. 43–51 min · Analyze and synthesize. Display the data-analysis and discussion slides. Groups graph temperature versus time, compare slopes, and write a claim-evidence-reasoning conclusion. They must use at least two pieces of evidence: their measurements or provided data and one explanation from the worksheet reading. Discuss why a faster temperature change does not automatically mean an object contains more total thermal energy. Teacher checks graphs, units, and whether conclusions distinguish temperature from energy.

6. 51–56 min · Misconception check and revision. Students respond to four statements on the misconception check: “Cold contains no thermal energy,” “Heat and temperature are interchangeable,” “Radiation requires matter,” and “A positive ΔU always means temperature increased.” Students label each true or false and revise one false statement using precise scientific language. Review responses with brief cold calls and clarify that internal energy can change during a phase change without a temperature change.

7. 56–60 min · Exit ticket and homework. Finish with the plenary and exit-ticket prompt. Students submit: (1) define temperature and thermal energy in one or two sentences; (2) identify the dominant transfer when sunlight warms pavement; (3) calculate ΔU when Q = −80 J and W = 20 J; and (4) summarize the investigation’s central conclusion in one sentence. Homework: write a 150–200-word explanation of how a thermos reduces conduction, convection, and radiation, including one labeled sketch and one correctly signed first-law calculation.

Resources

• the complete thermodynamics slide deck
• the thermodynamics notes and investigation worksheet
• Low-temperature lamp or sunny window
• Equal-sized metal and wood samples
• Digital thermometers or temperature probes
• Stopwatch or classroom timer
• Graph paper, rulers, pencils, and calculators
• Safety goggles and heat-resistant gloves if needed
• Prepared data set for groups without equipment

Assessment

• Formative checks: prediction justification, vocabulary questions, sign-convention calculations, and teacher observation of procedural accuracy.
• Collect or inspect group graphs for SI units, labeled axes, sensible comparisons, and evidence-based conclusions.
• Exit ticket assesses concepts, transfer mechanism, quantitative reasoning, and technical summarization. Use responses to group students for the next lesson’s review.

Differentiation

• Support: provide a partially completed data table, a graph template, equation rearrangement prompts, a sign-convention color key, and sentence starters such as “The data show…” and “This supports the idea that…”
• EAL and students needing language support: preteach system, surroundings, transfer, average, and internal; pair terms with diagrams and allow oral rehearsal before writing.
• SEN/access: offer digital probes, enlarged worksheet text, assigned group roles, calculator access, and a teacher-prepared data set; reduce copying while retaining the reasoning tasks.
• Extension: students calculate the percentage difference between samples’ temperature changes, propose a controlled test of sample mass or surface color, or analyze a case where work is done on the system.