Tsunamis Explained

Overview

In this lesson (7 of 18) on “Unraveling Our Changing Earth”, students investigate how tsunamis form and how tectonic processes can trigger them. They build explanations using diagrams and a short video, then apply learning to a short scenario task.

Learning intentions

• Students will be able to describe what a tsunami is and how it differs from ordinary waves.
• Students will be able to explain the relationship between tectonic events (earthquakes and seabed movement) and tsunami generation.
• Students will be able to use a simple model/diagram to explain how energy is transferred and waves propagate.

Success criteria

• I can describe the key stages in tsunami formation (seafloor disturbance → displaced water → wave propagation).
• I can use scientific terms correctly (e.g., tectonic plates, earthquake, seabed uplift/subsidence, wave propagation).
• I can interpret a diagram/video sequence to support my explanation.
• I can make a clear cause-and-effect statement about how tectonic events lead to tsunamis.

Curriculum links

• Earth systems: interactions involving tectonic activity and hazards.
• Science as a human endeavour: evidence-based explanation from observations and scientific modelling.
• Using scientific literacy: interpreting diagrams and supporting claims with reasoning.
• Skills: communicating ideas clearly using scientific language and representations.

Lesson structure (60 minutes)

1. 0–5 min: Hook + WALT

• Display a short, captioned image of a coastline affected by a tsunami. Ask: “What features make this look different from storm waves?”
• Share the lesson purpose: “WALT: Tsunamis Explained” and briefly outline the focus on tectonic causes and formation.

2. 5–12 min: Concept check with quick questions

• Do a fast class poll (hand signals) for statements such as “Tsunamis are caused only by earthquakes on land” and “Tsunamis involve displacement of seawater.”
• Correct misconceptions by building toward the core idea: seafloor movement is the trigger for many tsunamis.

3. 12–22 min: Video (with pause-and-predict)

• Play a short video sequence showing earthquake → seabed movement → tsunami waves travelling.
• Pause at three key moments. Students predict what will happen next and record one sentence each in their own words (or draw a simple arrow diagram if writing is difficult).

4. 22–35 min: Diagram model (teacher-led to guided practice)

• Use a whiteboard/slide diagram with cross-sections: tectonic plate boundary, seabed uplift/subsidence, water displacement, wavefront propagation.
• Students complete a “Cause → Process → Effect” chart using word bank cards (support) or full sentences (challenge).
• Emphasise cause-and-effect linking to tectonic events and energy transfer through the ocean.

5. 35–48 min: Small-group explanation task

• In groups of 3–4, students receive a scenario prompt: “A magnitude earthquake occurs near a subduction zone; community reports rapid sea-level change followed by a wave arrival.”
• Task: write or create a 6-step explanation of tsunami formation and propagation, using at least two scientific terms and one diagram/label.
• Circulate with prompts: “What displaced the water?” “How does the wave travel across the ocean?” “What changes are seen near the coast?”

6. 48–55 min: Whole-class sharing (one-minute explanations)

• Each group shares one key step and their evidence from the diagram/video sequence.
• Teacher consolidates into a class “Tsunami Formation Model” summary.

7. 55–60 min: Exit ticket (individual assessment)

• Students answer: “Explain, in 4–6 sentences, how tectonic events can lead to a tsunami.”
• Provide a diagram-label option for students who struggle with writing.

Resources

• Captioned tsunami/tectonic video (short, age-appropriate)
• Tsunami cross-section diagrams (print or slide)
• Word bank: tectonic plates, earthquake, seabed uplift, subsidence, displacement, wavefront, propagation, hazard
• Cause → Process → Effect chart template
• Scenario prompt cards (one per group)
• Coloured pencils/markers for diagram arrows
• Exit ticket slips with diagram-label option
• Dyslexia-friendly reading supports: sentence starters, larger-font handouts, reduced text density

Assessment

• Formative: teacher checks students’ predictions during video pauses and reviews group charts for accurate cause-and-effect.
• Formative/summative (exit ticket): evaluates students’ ability to describe formation steps and link them to tectonic events.
• Observation: monitors correct use of key terms and clarity of scientific explanations.

Differentiation

• Support for struggling literacy: allow drawing and labelled diagrams; provide sentence starters and word bank cards; use larger-font, short-text instructions.
• Support during group work: assign roles (diagram leader, writer, term checker, presenter) so all students contribute.
• EAL learners: provide illustrated vocabulary cards and a bilingual/visual example of “cause → process → effect”; encourage oral explanations before writing.
• Extension for advanced learners: require including “arrival time” factors (distance from source, wave speed concept) and compare two tsunami generation mechanisms (uplift vs subsidence) using the model.
• Dyslexia-friendly options: give audio read-aloud of scenario prompt, reduce copying load, and accept oral responses recorded by teacher or in short bullet form.

Extension (optional)

• Students research one historical tsunami event relevant to tectonic settings (e.g., subduction zone or plate boundary). They produce a brief report or infographic answering: what tectonic event occurred, what the tsunami formation looked like (using a simple diagram), where impacts occurred, and one safety/response lesson learned.