Lesson 2: Energy Flow: Producers, Consumers & Trophic Levels
Exploring NZ ecosystems, biodiversity, energy flow, invasive pests, kaitiakitanga, and field restoration projects.
🎯 Ngā Whāinga Akoranga | Learning Intentions
Photosynthesis as primary energy input (sunlight → chemical energy), producers (autotrophs), primary/secondary/tertiary consumers (heterotrophs), decomposers, and the 10% energy transfer rule.
Construct energy pyramids, calculate energy loss (90% heat/metabolism loss per level), and explain why top predators require large ecosystem ranges.
🎥 Media Anchor & Pedagogical Scaffold
Energy Flow in Ecosystems & The 10% Rule
Video Clip: Energy Flow in Ecosystems — Food Chains and Food Webs (Watch in full — declared full-watch).
🧠 1. Before Viewing (Activate & Predict)
Where does all the energy in a bush ecosystem originally come from, and why are there always fewer apex predators than plants?
👁️ 2. During Viewing (Watch With a Job)
- As you watch: Trace how energy moves from solar energy through producers (photosynthesis) to consumers.
- Note: What is the approximate percentage of energy passed between trophic levels? How does this explain energy pyramids?
- Consider: What role do decomposers play in recycling nutrients back to the soil?
🗣️ 3. After Viewing & Kaiako Move (Process & Apply)
Kaiako Move: Use physical 'Energy Token' activity where students transfer tokens between trophic levels to visualise energy loss.
Immediate Task: Complete Section 2 of your Ecology Field Journal: Trophic Pyramid & Energy Transfer Math Sheet.
⚡ Whakaoho | Do Now: Trace the Energy Back (10 mins)
Open your Section 1 matrix from last lesson and pick one living thing you recorded. Where does its energy come from? Trace the chain back as far as you can and write it with arrows (e.g. blackbird ← worm ← dead leaves ← sun). Pair-check: does every chain end at the same place? Today explains why — and why so much energy vanishes at every arrow.
📖 Activity 1: Energy Token Game — Prove the 10% Rule (25 mins)
- Set up (5 min): groups of four. Each person takes a role card: producer (e.g. kahikatea), primary consumer (e.g. wētā), secondary consumer (e.g. pīwakawaka), apex predator (e.g. kārearea). The producer starts with 100 tokens — the energy captured from sunlight.
- Transfer (10 min): pass energy up the chain, but only 10% survives each hand-over: 100 tokens → 10 → 1 → 0.1 (cut a token if you have to). The other 90% is "spent" — set it aside and label it: movement, body heat, waste, uneaten parts.
- Build the pyramid (5 min): draw an energy pyramid from your actual token counts, labelling each trophic level and its energy.
- Answer in pairs (5 min): why can a forest feed thousands of wētā but only a handful of kārearea? Why do apex predators need enormous territories? Use your token numbers as evidence.
📝 Activity 2: Field Journal Section 2 — Trophic Pyramid (20 mins)
Write up Section 2 of your Ecology Field Journal: your labelled energy pyramid with the token maths shown (100 → 10 → 1 → 0.1), a sentence explaining where the missing 90% goes at each level, and a worked answer to: "If a pest ate half the producers in this system, how much energy would reach the apex predator?" Use producer, consumer, trophic level and the 10% rule correctly.
🏫 Kaiako Planning & Pedagogy Notes
Prep: 100 counters per group — anything works (beans, cubes, paper squares). Make every group compute 100 → 10 → 1 → 0.1 themselves rather than watch a demo; the arithmetic IS the learning. Misconception to surface: energy is not "used up and gone" — it leaves the food chain as heat, movement and waste. The pyramid feeds directly into next lesson's food web. Curriculum anchoring for the unit sits on the unit page (verbatim Te Mātaiaho statements).