| Lesson Plan |
| Grade: |
Date: 25/02/2026 |
| Subject: Physics |
| Lesson Topic: understand how the reflection of pulses of ultrasound at boundaries between tissues can be used to obtain diagnostic information about internal structures |
Learning Objective/s:
- Describe the principle of pulse‑echo ultrasound and how reflections arise at tissue boundaries.
- Calculate acoustic impedance and the reflection coefficient for given tissue pairs.
- Use the time‑of‑flight equation to determine the depth of a reflecting interface.
- Interpret B‑mode image brightness to identify different tissue types.
- Evaluate limitations of ultrasound imaging such as attenuation and acoustic shadowing.
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Materials Needed:
- Projector and screen
- Laptop with ultrasound simulation software
- Printed handout of tissue acoustic impedances and formulas
- Calculator or spreadsheet
- Whiteboard and markers
- Sample B‑mode ultrasound images for analysis
- Piezoelectric transducer demo kit (optional)
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Introduction:
Begin with a short video clip of a real‑time fetal ultrasound scan, asking students what enables the machine to “see” inside the body. Recall previous learning about wave speed, frequency and acoustic impedance from earlier physics topics. State that by the end of the lesson they will be able to predict echo strength, calculate the depth of internal structures, and interpret basic ultrasound images.
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Lesson Structure:
- Do‑now (5') – quick quiz on wave speed and impedance formulas.
- Mini‑lecture (10') – overview of ultrasound generation, piezoelectric transducers, and pulse‑echo mode.
- Interactive derivation (10') – calculate Z and R for two tissue examples using the handout.
- Simulation demonstration (8') – show pulse propagation and echo formation; discuss the time‑of‑flight concept.
- Guided practice (12') – pairs work on worksheet to compute depths and interpret echo brightness from sample images.
- Class discussion (8') – share answers, address misconceptions, link to clinical applications.
- Summary checklist (5') – teacher reviews key points; students self‑check using the checklist.
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Conclusion:
Recap the connection between acoustic‑impedance mismatches, echo intensity, and the time‑of‑flight formula for locating structures. Students complete an exit ticket: one depth calculation and a brief interpretation of an echo pattern. For homework, each student researches a specific clinical ultrasound application and writes a short paragraph describing how pulse‑echo principles are used.
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