Pregnancy Ultrasound

Overview

Today’s self-directed Health learning links Hauora wellbeing with a physics-informed explanation of pregnancy ultrasound. You will use a mini “slide pack” to build a clear chain of cause-and-effect: wave production → sound use → reflection/echoes → image formation → gel and tissue differences.

Learning intentions

• WALT explain how ultrasound waves are produced in an ultrasound machine.
• WALT explain why ultrasound uses sound instead of X-rays in pregnancy imaging.
• WALT describe reflection and echoes and how they contribute to image formation.
• WALT explain how a developing baby’s image is formed from returning echoes.
• WALT justify why ultrasound gel is used and why different tissues produce different images.

Success criteria

• I can explain (in sequence) how ultrasound creates an image of a developing baby.
• I can state why sound (ultrasound) is used instead of X-rays.
• I can use “reflection/echo” to describe how information becomes an image.
• I can explain why gel and tissue differences change image brightness/appearance.

Curriculum links

• Hauora — Health and wellbeing: understanding technologies that support safe wellbeing during pregnancy.
• TMoA Hauora framing — human wellbeing in a holistic model, recognising the role of accurate health information for whānau wellbeing.
• Hauora learning is supported by demonstrating understanding of how technologies work in health contexts (teaching for informed wellbeing decisions).

Lesson structure (1 minutes)

1. 0–5 sec · Start & expectations. Teacher displays the slide pack title “Pregnancy Ultrasound—How Images Are Made” and reads the task: complete Slide 1–5. Students open the self-directed sheet and confirm they will write short, clear explanations for each prompt.

2. 5–25 sec · Slide 1: Wave production. Teacher directs students to read Slide 1 and fill in the “My explanation” box using 3–4 sentences. Students write: how electrical energy in the probe becomes mechanical vibration that produces ultrasound waves.

3. 25–40 sec · Slide 2: Sound not X-rays. Teacher pauses and reminds students to compare risk/beam type in a health context (sound vs ionising radiation). Students write: why ultrasound uses sound (non-ionising) rather than X-rays (ionising radiation) for pregnancy imaging.

4. 40–55 sec · Slide 3: Reflection & echoes. Teacher points students to the “echo pathway” diagram and the key words “reflect → travel back → echo”. Students annotate the pathway and write a short explanation of reflection and echoes.

5. 55–60 min · Slide 4–5: Image formation + gel + tissue differences. Teacher quickly instructs students to complete one combined response: “How the machine creates an image” using prompts from Slides 4 and 5. Students write a final response answering: how the returning echoes form an image, why gel is needed, and why tissues produce different images.

Resources

• Printed or digital slide pack for students: “Pregnancy Ultrasound—How Images Are Made” (Slides 1–5)
• Pen/pencil and a lined response page or shared document template
• Diagram templates included in the slide pack (probe → waves → baby/tissues → echoes → display)
• Optional timer visible to students (60 seconds total)

Assessment

• Formative: teacher checks completed Slide 1–5 during the final minute (scan for key ideas: produced → sound vs X-rays → reflection/echoes → image formation → gel/tissue differences).
• Achievement check (teacher quick read of final combined response): accuracy of explanation sequence and use of relevant physics terms.
• Evidence collected: student’s “Possible assessment question” paragraph.

Differentiation

• Support: provide sentence starters on the sheet, e.g., “The probe contains…”, “Ultrasound is…”, “When waves hit a tissue, they…”, “The gel helps because…”.
• Support: allow diagrams to count as part of explanation (label parts of the pathway: probe, waves, reflection, echoes, screen).
• Extension: students add one extra sentence linking image quality to factors such as angle of incidence or tissue density (keeping it understandable).
• EAL/SEN: reduce word count requirement per slide (2–3 sentences), emphasise key terms with a word bank.

Slide pack (student self-directed)

Slide 1 — How ultrasound waves are produced Prompt: In an ultrasound machine, how are ultrasound waves made? My explanation (3–4 sentences):

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Key words to include: probe, electrical energy, vibration, ultrasound waves.

Slide 2 — Why sound, not X-rays Prompt: Explain why ultrasound uses sound instead of X-rays for pregnancy imaging. My explanation (2–3 sentences):

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Key words to include: sound waves, non-ionising, safe imaging.

Slide 3 — Reflection and echoes Prompt: Describe what happens when ultrasound waves meet different tissues. My explanation (3–4 sentences):

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Key words to include: reflection, echoes, travel back, pattern of return.

Slide 4 — Image formation Prompt: Explain how the ultrasound machine turns echoes into an image of the developing baby. My explanation (2–3 sentences):

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Include: how the timing/strength of echoes helps the machine build a picture.

Slide 5 — Gel and different tissue images Prompt: Why is gel needed? Why do different tissues produce different images? My explanation (3–4 sentences):

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Include: gel removes air (improves contact), tissues reflect differently, image brightness/contrast.

Possible assessment question (final response) Explain how an ultrasound machine creates an image of a developing baby. Write your final paragraph (5–7 sentences).

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