Lesson: Microorganisms

Year: 6 | Subject: Science | Time Allocation: 100%

Class/Set: ____________ Date/Term: ____________

LO (WALT): To classify different types of microorganisms and explain their various roles in the environment.

Success Criteria (WILF):

1. I can define what a microorganism is and name three main types: bacteria, viruses, and fungi.
2. I can distinguish between 'helpful' and 'harmful' microorganisms using specific real-world examples.
3. I can describe the conditions microorganisms require to grow and reproduce.

1. Starter (15%)

• Facilitate: Present students with a series of high-definition 'mystery' images of magnified microorganisms (e.g., bread mould, bacteria on a kitchen sponge, yeast cells).
• Question: Ask students to examine the images and discuss in pairs: "Are these living things? Why/Why not?"
• Retrieve: Link back to 'MRS GREN' (life processes) to establish that these are indeed living organisms, despite their microscopic size.

2. Main Activity (70%)

Teacher Input:

• Define: Introduce the term 'microbe' as a synonym for microorganism. Explain that they are single-celled organisms that can only be seen with a microscope.
• Explain: Categorise microbes into three main groups: Bacteria (e.g., those found in yoghurt vs. those that cause tooth decay), Viruses (e.g., the common cold), and Fungi (e.g., yeast or mushrooms).
• Model: Create a T-table on the whiteboard titled 'Helpful' and 'Harmful'. Demonstrate how to place 'Yeast' (Fungi) in the helpful column for bread-making, and 'Influenza' (Virus) in the harmful column.
• Discuss: Introduce the concept of 'decay'. Explain how microorganisms are essential for breaking down organic matter in the environment, which is a 'helpful' process for the planet but can be 'harmful' if it happens to our food.
• Check: Use mini-whiteboards to ask: "Which group does 'mould' belong to?" and "Is all bacteria bad for humans?"

Student Task:

• Investigate: Provide students with 'Microbe Fact Files' detailing five different microorganisms (Lactobacillus, Penicillium, Yeast, E. coli, and Influenza).
• Classify: Complete the Classification Table below by identifying the type of microorganism and its impact.
• Reason: Explain in two sentences why we might describe a decomposer (like fungi on a fallen log) as 'helpful' to an ecosystem but 'harmful' to a homeowner.
• Predict: List three environmental conditions (e.g., temperature, moisture) that would cause bread mould to grow more quickly.

Microorganism	Type (Bacteria/Virus/Fungus)	Helpful or Harmful?	Reason
Lactobacillus	Bacteria	Helpful	Used to turn milk into yoghurt.
Yeast	Fungus	Helpful	Makes bread rise.
Influenza	Virus	Harmful	Causes the flu.
Penicillium	Fungus	Helpful	Used to create life-saving antibiotics.
E. coli	Bacteria	Harmful	Can cause severe food poisoning.

3. Plenary (15%)

• Consolidate: Conduct a 'Microbe True or False' quiz.
• Evaluate: Ask: "If we wiped out every single microorganism on Earth tomorrow, would humans survive?"
• Summarise: Ensure students understand that while some cause disease, many are vital for digestion, food production, and decomposition.

4. Resources

• Magnified images of microbes.
• Microbe Fact Files.
• Classification Table worksheets.
• Mini-whiteboards and pens.
• Sample of mouldy bread (sealed in a double-layered transparent bag for safety).

---

⚠ TEACHER’S GUIDANCE

💡 Pedagogical Pulse

• Misconception Alert: Many Year 6 students believe all 'germs' are bacteria or that all microorganisms are 'bad'. Explicitly highlight the role of bacteria in the gut and yeast in food to provide a balanced view.
• Scientific Inquiry: This lesson provides a strong foundation for a follow-up 'Fair Test' investigation into bread mould growth. Encourage students to think about variables such as light, temperature, and moisture.
• Vocabulary: Ensure students are using the Tier 2 term examine and the Tier 3 term microorganism correctly throughout the session.

✅ Answer Key & Solutions

• Task: Classification Table

  • Lactobacillus: Bacteria | Helpful (Yoghurt production).
  • Yeast: Fungus | Helpful (Baking/Fermentation).
  • Influenza: Virus | Harmful (Illness).
  • Penicillium: Fungus | Helpful (Medicine/Antibiotics).
  • E. coli: Bacteria | Harmful (Food poisoning/Infection).

• Task: Reasoning (Decomposers)

  • Model Answer: A decomposer is helpful to an ecosystem because it recycles nutrients back into the soil for plants to grow. It is harmful to a homeowner because it can cause the wooden structure of a house to rot and become unsafe.

• Task: Prediction (Conditions for growth)

  • Expected Answers:
    1. Warmth: Higher temperatures speed up the reproduction of microbes.
    2. Moisture: Microorganisms need water to carry out life processes.
    3. Nutrients/Food: Sugar or starch (like in bread) provides energy for growth.

⚠ Safety & Nuance Check

☐ Ensure any physical samples of mouldy bread are double-bagged and securely taped shut. Do not allow students to open the bags, as mould spores can trigger allergic reactions or respiratory issues. ☐ When discussing viruses, maintain a neutral and calm tone to avoid causing anxiety regarding recent global health events. Focus on the biological structure rather than the social impact.