ecosystems
4 detailed 50-minute lessons with teaching scripts, worked examples, parent guides, and assessment criteria.
Lesson Overview
Total Lessons: 4
Tier: Foundation and Higher
Duration: 50 minutes per lesson (200 minutes total)
Exam Boards: AQA, Edexcel, OCR, Eduqas, CCEA
Tier: Foundation and Higher
Duration: 50 minutes per lesson (200 minutes total)
Exam Boards: AQA, Edexcel, OCR, Eduqas, CCEA
Learning Objectives
- Explain the key ideas of ecosystems
- Apply ecosystems to exam-style questions
- Develop independent study skills
- Build cross-topic connections
Prerequisites
- Read the revision notes for ecosystems first (GCSE Revise summary)
- Key vocab to pre-teach: Ecosystems
- Basic skills: reading the summary notes and answering the practice questions there
Materials & Equipment
- Exercise book, coloured pens
- Scientific calculator
- Ruler
- Printed revision notes (link below)
- Internet for videos (see Resources)
Lesson 1: Introduction: ecosystems
Duration: 50 minutes
Starter Activity (5 minutes)
Quick Recall
Write down everything you already know about ecosystems. Then check against the key terms: Ecosystems. Use a mini-whiteboard or paper.
Main Content (35 minutes)
Parent/Teacher Guide:
Before lesson: Read the script below. Pre-teach key vocab: Ecosystems.
If stuck: Re-read the revision notes (link above), then break the content into smaller steps.
Extension: See the Stretch & Challenge ideas in Lesson 4.
Before lesson: Read the script below. Pre-teach key vocab: Ecosystems.
If stuck: Re-read the revision notes (link above), then break the content into smaller steps.
Extension: See the Stretch & Challenge ideas in Lesson 4.
Teaching Script (35 mins):
Mins 0-5 - Hook: "Today: ecosystems. By the end you will be able to answer exam questions on it unaided. It connects to the rest of Biology because the ideas here recur across the spec."
Mins 5-20 - Direct Instruction: Work through the core ideas below one at a time; after each, ask your student to explain it back in their own words.
Mins 20-30 - Guided Practice: Model the worked example together, then let your student attempt the first practice question with guidance.
Mins 30-35 - Independent Practice: 2-3 practice questions from Lesson 3 below, with immediate feedback.
Mins 0-5 - Hook: "Today: ecosystems. By the end you will be able to answer exam questions on it unaided. It connects to the rest of Biology because the ideas here recur across the spec."
Mins 5-20 - Direct Instruction: Work through the core ideas below one at a time; after each, ask your student to explain it back in their own words.
Mins 20-30 - Guided Practice: Model the worked example together, then let your student attempt the first practice question with guidance.
Mins 30-35 - Independent Practice: 2-3 practice questions from Lesson 3 below, with immediate feedback.
First Look
Start with the revision notes summary, then attempt: Define the terms: ecosystem, community, population and habitat.
Plenary (5 minutes)
Check Out
Your student states one thing they learned and one question they still have about ecosystems.
Lesson 2: Core Concepts: ecosystems
Duration: 50 minutes
Starter Activity (5 minutes)
Review Previous Lesson
Quick recap: write 3 key points from Lesson 1 on ecosystems. Check them against the notes below.
Main Content (35 minutes)
Ecosystems: An ecosystem is the interaction of a community of living organisms with the non-living (abiotic) parts of their environment. Organisms are interdependent — they rely on each other for survival.
| Item | Detail |
|---|---|
| Ecosystem | The interaction of a community of living organisms with the non-living parts of their environment |
| Community | All the populations of different species that live together in the same area at the same time |
| Population | All the organisms of the same species living in the same area at the same time |
| Habitat | The place where an organism lives |
| Interdependence | Organisms within a community depend on each other for food, shelter, pollination, seed dispersal, etc. |
Practice (10 minutes)
Q: Define the terms: ecosystem, community, population and habitat.
Answer: Ecosystem: the interaction of a community of living organisms with the non-living parts of their environment. Community: all the populations of different species living in the same area at the same time. Population: all organisms of the same species living in the same area at the same time. Habitat: the place where an organism lives.
Plenary (5 minutes)
Explain Back
Your student teaches the key points back to you without looking. Fill any gaps immediately.
Lesson 3: Application: ecosystems
Duration: 50 minutes
Starter Activity (5 minutes)
Quick Recall
Recall the key terms: Ecosystems. Define each in one sentence.
Main Content (35 minutes)
Parent/Teacher Guide: Let your student attempt each question alone first, then compare with the model answer. Award method marks for correct working even if the final answer is wrong.
Q1: Define the terms: ecosystem, community, population and habitat.
Answer: Ecosystem: the interaction of a community of living organisms with the non-living parts of their environment. Community: all the populations of different species living in the same area at the same time. Population: all organisms of the same species living in the same area at the same time. Habitat: the place where an organism lives.
Q2: Explain the difference between competition and predation, giving an example of each.
Answer: Competition is when organisms compete for limited resources (e.g. plants competing for light). Predation is when one organism (predator) kills and eats another (prey) (e.g. foxes eating rabbits). Competition is between organisms of the same or different species; predation is between predator and prey species.
Q3: Describe the predator-prey cycle and explain why there is a time lag between changes in the prey population and changes in the predator population.
Answer: When prey increase, predators have more food and their population increases (with a time lag because predators need time to reproduce and grow). More predators eat more prey, so prey decrease. Less prey means predators decrease. Fewer predators means prey increase again. The time lag exists because reproduction takes time — predators cannot increase instantly when prey becomes more available.
Q4: Explain why a pyramid of biomass is always pyramid-shaped. Give three reasons why biomass is lost between trophic levels.
Answer: A pyramid of biomass is always pyramid-shaped because biomass is lost at each trophic level. Reasons for loss: (1) Not all parts of an organism are eaten (bones, fur, roots). (2) Not all food eaten is absorbed — some is egested as faeces. (3) Absorbed material is used for respiration, producing CO₂, water and heat. (4) Some material is excreted as waste (urea).
Q5: A producer has a biomass of 50,000 kJ/m². Estimate the biomass available to tertiary consumers and explain why food chains are rarely longer than 4-5 trophic levels.
Answer: Producer: 50,000 kJ/m². Primary consumers: ~10% = 5,000 kJ/m². Secondary consumers: ~10% = 500 kJ/m². Tertiary consumers: ~10% = 50 kJ/m². Food chains are rarely longer than 4-5 trophic levels because there is not enough energy/biomass remaining to support another level — only about 10% is transferred at each step.
Plenary (5 minutes)
Error Review
Review any questions answered incorrectly. Identify whether the error was knowledge, method, or reading the question.
Lesson 4: Exam Practice: ecosystems
Duration: 50 minutes
Starter Activity (5 minutes)
Command Words
Review what these command words require: state (one point), describe (say what happens), explain (say why), compare (both sides), evaluate (judgement).
Main Content (35 minutes)
Extended Answer
Extended question: Extended Answer 6 marks: Explain why pyramids of biomass are always pyramid-shaped and why food chains rarely have more than four or five trophic levels. <div class="
Pyramids of biomass are always pyramid-shaped because biomass is lost at each trophic level. Firstly, not all parts of an organism are eaten — for example, bones, fur, roots and hooves are left behind. Secondly, not all food that is eaten is absorbed; some is egested as faeces. Thirdly, absorbed material is used for respiration, which releases CO₂, water and heat energy. Fourthly, some absorbed material is excreted as waste, such as urea in urine. Only approximately 10% of the biomass is transferred from one trophic level to the next. Because so much energy is lost at each stage, there is not enough biomass remaining to support further trophic levels beyond four or five. At the tertiary consumer level, the biomass available may be only 0.1% of the producer biomass, which is insufficient to sustain another level. Mark scheme: 1 mark for not all parts eaten; 1 mark for egestion; 1 mark for respiration; 1 mark for excretion; 1 mark for ~10% transfer; 1 mark for explanation of why food chains are limited in length
Exam Tips: Learn the definitions of ecosystem, community, population and habitat precisely — these are frequently tested | In food chains, arrows go FROM the eaten TO the eater (showing energy flow) | Decomposers are NOT shown in food chains but are essential for recycling nutrients | When describing predator-prey cycles, always mention the TIME LAG | Only ~10% of energy/biomass transfers between trophic levels — use this in calculations | Pyramids of NUMBER can be inverted (e.g. one tree with many insects), but pyramids of BIOMASS are always pyramid-shaped | When explaining biomass loss, mention at least 3 reasons: not all eaten, egestion, respiration, excretion
Common Errors: Watch Out! 1. Wrong: A population is all the organisms in an area Correct: A population is all the organisms of ONE species in an area — a community includes all the different species 2. Wrong: Arrows in a food chain show who eats whom Correct: Arrows show the direction of energy flow, FROM the eaten TO the eater (e.g. grass → rabbit, not rabbit → grass) 3. Wrong: Pyramids of number are always pyramid-shaped Correct: Pyramids of NUMBER can be inverted (e.g. one tree with many insects) — only pyramids of BIOMASS are always pyramid-shaped 4. Wrong: Decomposers are shown in food chains Correct: Decomposers are NOT shown in food chains but are essential for recycling nutrients back into the soil
AO3 - Reasoning & Interpretation: 0 m (woodland edge): 0 dandelions per m² | 5 m: 2 dandelions per m² | 10 m: 8 dandelions per m² | 15 m: 14 dandelions per m² | 20 m (open field): 18 dandelions per m²
Stretch & Challenge (Grade 8-9):
- Synoptic links: explain how ecosystems connects to another Biology topic you have studied
- Real-world: research one real-world use or example of ecosystems
- Critical: "What are the limitations of the models used in ecosystems?"
Plenary (5 minutes)
Assessment Criteria
- Got it: Confident explanation + correct worked examples
- Getting there: Main points OK, needs support with detail
- Not yet: Confused on key concepts - re-run Lesson 2
Homework & Consolidation
- Consolidation: Re-answer any Lesson 3 practice questions answered incorrectly (20 mins)
- Retrieval: Write flashcards for the key terms: Ecosystems (10 mins)
- Exam practice: One past-paper question on ecosystems from the board websites (15 mins)
- Extension: Explain ecosystems to someone else in your own words (10 mins)