Lesson 5: Ocean Currents & Fluid Dynamics: Coriolis Effect & Gyres
Exploring physical phenomena—waves, forces, vectors, optics, and relativity—through traditional Polynesian navigation and ocean science.
🎯 Ngā Whāinga Akoranga | Learning Intentions
Global ocean current systems (South Equatorial Current, East Australian Current), the Coriolis effect caused by Earth's rotation, thermohaline circulation (density driven by temperature and salinity), and ocean temperature gradients.
Model Coriolis deflection on a rotating turntable, experiment with thermal and saline density layering, and map Pacific ocean gyres.
🎥 Media Anchor & Pedagogical Scaffold
How do ocean currents work? - Jennifer Verduin (TED-Ed)
Video (TED-Ed): An animated explainer on global ocean currents, including the Coriolis effect, thermohaline circulation, and how temperature and salinity drive the ocean's conveyor belt system.
🧠 1. Before Viewing (Activate & Predict)
How do massive ocean currents act like giant conveyor belts in the Pacific, and how did navigators utilise them for migration routes?
👁️ 2. During Viewing (Watch With a Job)
Watch the full 6-minute clip and collect evidence for these ocean current mechanisms:
- Wind-driven currents: How do winds push surface waters, and what role does the sun play?
- Coriolis Effect: How does Earth's rotation deflect moving water currents?
- Thermohaline circulation: What causes deep ocean currents, and how do temperature and salinity matter?
- Ocean conveyor belt: How do surface and deep currents connect in global circulation patterns?
🗣️ 3. After Viewing & Kaiako Move (Process & Apply)
Kaiako Move: Demonstrate a density tank with coloured hot saltwater vs cold freshwater showing thermal fluid layering.
Immediate Task: Complete Section 5 of your Navigation Physics Logbook: Coriolis Deflection Defiance & Gyre Mapping Sheet.
⚡ Whakaoho | Do Now: Draw a Straight Line on a Spinning Disc
With the turntable spinning, draw a line straight out from the centre. Then stop it and look at what you drew.
Your hand moved in a straight line. The line on the disc is curved. Nothing pushed the pen sideways. Two minutes: write down what that tells you — because that is the entire Coriolis effect, and it is not a force.
📖 Activity 1: Model the Deflection, Then Layer the Density
Three traces (13 min). Repeat the turntable trace spinning one way, then the other, then stationary. Record the curve direction each time. Then connect it to the real world: which rotation direction corresponds to the Southern Hemisphere, and which way are currents deflected here?
Density layering (12 min). Set up warm against cold, and fresh against salt, using dye. Record which layer sits above which and how sharply they separate. Say which variable had the stronger effect in your setup. That layering, at ocean scale, is what drives thermohaline circulation.
📝 Activity 2: Navigation Physics Logbook & Problem Solving (20 mins)
Portfolio Section 5. Submit: (1) three turntable traces with rotation direction labelled and the Southern Hemisphere case identified; (2) your density-layering results naming the stronger variable; (3) a mapped Pacific gyre showing the South Equatorial and East Australian currents, with an explanation of how a navigator uses a known current rather than fighting it.
🏫 Kaiako Planning & Pedagogy Notes
Year 10 Curriculum Alignment: NZ Curriculum Science Phase 4 — Physical World & Earth/Space Systems. Integrates traditional Polynesian wayfinding (Mātauranga Waka) with foundational NCEA Level 1 Physics mechanics, wave behaviour, and optics.