📚 Unit Plans → 🌍 Y7 Science: Ecosystems & Kaitiakitanga → 📖 Lesson 2: Food Chains & Food Webs (Y7)
Year 7 Pūtaiao / Science

Lesson 2: Food Chains & Food Webs

Build a local food web, test a disruption, and keep scientific inference separate from any locally authorised seasonal knowledge.

Do NowWhere does the energy come from?8 mins BuildProducer, consumer, decomposer12 mins MakeThree chains into one class web18 mins TestPull one species out12 mins WriteOne pathway, explained10 mins

Tirohanga Whānui | Overview

Lesson 1 established that the parts of an ecosystem affect each other. This lesson makes energy pathways visible and testable: ākonga build a food web from species recorded in their field journals, then model a decline. If the kura has a locally authorised seasonal observation or harvest guideline, the class can examine how it changes a decision. It must not turn a generic “maramataka calendar” into local mātauranga.

Ngā Whāinga Ako | Learning Intentions

  • Sort local species into producers, consumers and decomposers.
  • Build a food web that traces energy from the sun onward.
  • Predict what happens to the web when one species declines.

Ngā Paearu Angitū | Success Criteria

  • My arrows point the way the energy travels, not the way the animal moves.
  • My web includes at least one decomposer.
  • I can name two species affected when one selected species declines, and say why.

Do Now: Where did the energy come from?

8 mins

Run it

  1. Prompt (2 min): "You ate breakfast this morning. Trace that energy backwards as far as you can go. Where does the trail stop?"
  2. Share (4 min): take three or four trails aloud. For ordinary classroom food examples, the trail should reach a plant or alga that captured sunlight. Let students find that step rather than announcing it first.
  3. Name it (2 min): “Today our model follows sunlight through a local food web. Other ecosystems can use chemical energy, but that is outside this model.”

Build: Three jobs in a system

12 mins

Run it

  1. Define (4 min): producers make their own food from sunlight (harakeke, rimu, phytoplankton) · consumers eat other organisms (tuna, kererū, kōura, us) · decomposers break the dead down and return nutrients to the soil (fungi, bacteria, worms).
  2. Sort local species (8 min): each group copies six organisms from its field journal onto scrap-card rectangles, then sorts them into the three roles. Add a teacher-supplied decomposer if none was observed. Argue the hard ones: fungi are neither plants nor animals, but decomposition still returns nutrients to the system.

Common misconception: students draw arrows from the eater to the eaten. The arrow follows the energy, so it points from the eaten to the eater. Correct this early or it persists all unit.

Make: From three chains to one web

18 mins

Run it

  1. Chains (7 min): each pair builds three food chains from the species cards, starting with a producer.
  2. Combine (9 min): bring the chains to a wall or whiteboard and connect any species that appears in more than one. The tangle that results is the food web, and the tangle is the point.
  3. Notice (2 min): "Which species has the most arrows touching it?" That one is load-bearing.

Mātauranga connection

Use only a local source approved by the kura or mana whenua. If that source supplies a seasonal tohu or harvest guideline for one species, ask: what decision does it change, and what relationship in the web helps explain the consequence? Record the source beside the annotation. If no local source has been supplied, use published breeding-season data for a local species and label it as scientific evidence; do not invent a maramataka rule.

Test: Pull one out

12 mins

What it is: The experiment that turns the diagram into an argument.

Run it

  1. Remove (4 min): physically take one species card off the wall, ideally the one with the most arrows. "This species has declined to almost nothing. Which arrows break?"
  2. Follow it (6 min): trace the consequences two steps out. Who goes hungry? Who gets more numerous with nothing eating them? What happens to the producers then?
  3. Second round (2 min): remove a decomposer instead. Students usually expect little to happen and are surprised.

Kaiako move: resist naming the answer. The point is that students discover a change two steps away from the species that was removed. That is what "interdependence" means and it is hard to un-see once traced.

Write: One pathway

10 mins

Formative task

Students annotate their own food web diagram and write a short explanation of one interdependence pathway: name the species, follow the energy, and state one thing that would change if a link broke.

Marked on three things: scientific accuracy (arrows point the right way, roles correct) · clarity (a reader can follow the path) · connection to place (real local species, not generic textbook ones).

Differentiation

More support: the kaiako pre-fills six scrap cards from the group's field journal and supplies a partly built chain to extend rather than a blank start.

Extension: ask what happens to a food web when a species arrives that has no predators here. That is Lesson 3 and they will have thought about it first.

Assessment note: the arrow-direction error is the single most common one at this level. Check direction before marking anything else.

Curriculum alignment

"Energy transfers and nutrients flow through food chains and food webs, through producers, consumers, and decomposers, and including processes such as photosynthesis and respiration."
"Ecosystems are composed of biotic and abiotic factors, which interact with each other and are important to the survival of organisms."

Ākonga teach both statements through the organism-role sort, arrow-direction model, combined class web, and two-step disruption test.

Next: Lesson 3 — Human Impacts & Kaitiaki Action