Surviving Selection Pressures

Overview

Subject: Science
Year Level: Year 11
Module: Biological Diversity (Module 3)
Focus Outcome:

• BIO11/12-10: Describes biological diversity by explaining the effects of evolutionary mechanisms.
• BIO11-6: Analyses environmental and ethological data to predict the effect of environmental changes on organisms.

Lesson Duration: 50 minutes
Class Size: 25 students
Key Literacy Focus: Tier 2 and Tier 3 vocabulary | Scientific communication | Evaluating data sets

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Learning Intentions

By the end of the lesson, students will be able to:

• Define and understand the concept of selection pressures.
• Predict and explain the effects of different selection pressures on populations in ecosystems.
• Use biological terminology to explain how environmental changes can influence the survival and reproduction of organisms.
• Engage in scientific reasoning, evidence-based prediction, and academic discussion.

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Success Criteria

Students will:

• Identify at least three types of selection pressures.
• Analyse a real-world or simulated ecosystem scenario.
• Apply understanding to predict evolutionary responses in a given population.
• Use scientific terms effectively in their answers and verbal contributions.

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Australian Curriculum Alignment (NSW Stage 6)

Strand: Stage 6 Science – Biology
Module 3: Biological Diversity
Focus Inquiry Question:

• "Why do populations change over time?"
  Content Descriptor:
• Analyse how the theory of evolution by natural selection explains the diversity of living things and is supported by a range of evidence (ACSBL084)
• Predict the effect of selection pressures on a population using secondary sources (ACSBL086)

Literacy Capabilities:

• Comprehending texts (interpreting scientific descriptions and stimulus)
• Composing texts (explanations and predictions using scientific vocabulary)
• Vocabulary development: Use of domain-specific Tier 3 terms (e.g. ‘adaptation’, ‘allele frequency’, ‘genotype’) alongside Tier 2 academic language (e.g. ‘determine’, ‘predict’, ‘analyse’)

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Materials Needed

• Whiteboard and markers
• Student handouts with selection pressure scenarios (printed)
• Access to devices (if available – optional for interactive quiz)
• Images or short videos depicting real cases of evolution from selection pressure (e.g. peppered moths, antibiotic resistance, cane toads in Australia)
• Word wall or anchor chart vocabulary sheet

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Lesson Sequence

1. Engage (5 minutes)

Activity: Fast Facts Brainstorm – “What Would You Do?”

• Display image of a rapidly changing environment (e.g. a drought-stricken savannah or coral bleaching event).
• Ask students: “If you were a species living here, what traits would help you survive?”
• Record ideas on the whiteboard. Group answers later into categories: physical adaptations, behavioural adaptations, physiological traits.

Literacy element: Encourage complete sentence responses. Prompt students to use cause-effect sentence starters: “If the environment changes…, the organism would need to…”

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2. Explore (10 minutes)

Mini Lecture: Selection Pressures Defined

Using annotated visuals and short storytelling segments, introduce:

• Definition of selection pressure (abiotic vs biotic)
• Examples: predation, limited resources, climate, disease, invasive species
• Effects on populations over time: allele frequency shifts, adaptations, survival rates

TEACHER TIP: Relate back to Australia-specific organisms — kangaroo response to drought, cane toad impact on native predators, koalas and eucalyptus availability.

Literacy focus area: Introduce 3 new domain-specific words: adaptation, genetic variation, selection. Add them to a visible Word Wall with student-generated definitions.

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3. Apply (15 minutes)

Group Activity: Survival Scenario Investigation

Instructions:

• Students in groups of 5.
• Each group is given a card with a unique ecosystem challenge (e.g. sudden climate cooling, introduction of a new predator, human-driven habitat destruction).

They must:

1. Identify the selection pressure(s).
2. Predict how a focal species would be affected.
3. Describe possible evolutionary responses the population could show over generations.

Group Report Back (quick-fire):
Each group gives a 30-second summary using this scaffold:

“Our species is a [organism]. The selection pressure is ____. As a result, we predict that ____ will happen because ____.”

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4. Consolidate (15 minutes)

Class Discussion + Literacy Construction – Selection Pressure Chain

As a class, build a cause-effect chain on the board from environment to evolution using specific vocabulary:

“Change in environment → new selection pressure → differential survival → shift in population traits → evidence of evolution”

Literacy Focus:
Prompt students to improve wording for academic clarity. For example:

• Swap “things die” with “organisms lacking adaptive traits are less likely to survive and reproduce.”

Optional consolidation task:

• Self-assessment quick write (3 minutes): “How do selection pressures drive evolution in ecosystems?”
• Students circle vocabulary used from the Word Wall – aim for at least three Tier 3 words.

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5. Exit Ticket (5 minutes)

Quick Quiz: True or False?

Hand students a slip with 5 True/False statements, such as:

• Selection pressures can be biotic or abiotic.
• All mutations help organisms survive selection pressures.
• If an individual changes traits during its life, its offspring will inherit these.
• Evolution occurs in individuals, not populations.
• Natural selection cannot happen without variation.

Students circle answers. Discuss key misconceptions as a class.

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Differentiation Ideas

• Extension: Invite high achieving students to develop their own selection pressure scenario with a proposed evolutionary outcome.
• Support: Pair EAL/D students with peers and provide a simplified glossary of terms. Include images where possible.
• All learners: Use colour-coded graphic organisers to visually break down cause-effect sequences.

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Homework / Optional Extension

Creative 2-minute pitch:
Ask students to write from the perspective of a species facing a new threat:

“Convince us that your species will survive!”

They must argue using scientific logic to explain:

• The nature of the threat
• Traits that will persist or develop through selection
• Why your species will not go extinct

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Teacher Reflection Prompt

To be completed after the lesson:

1. Were students able to independently identify cause-effect links in evolutionary examples?
2. Did literacy scaffolds improve the use of structured scientific language in student explanations?
3. How can the next lesson extend the understanding of selection over time (e.g. speciation, adaptation modelling)?

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Designed with the Australian Curriculum in mind, this lesson applies current, contextual examples of evolution and integrates functional literacy tasks, ensuring both engagement and rigour for Year 11 students.