L05 — Where Do We Draw the Line?
Module: M06 — Rewriting Life
Periods: 1
NGSS: HS-LS3-1, HS-LS3-2
Lesson Type: Evaluate
Learning Objective
- By the end of this lesson, students will be able to construct an evidence-based argument about the ethical boundaries of gene editing by engaging in a structured debate and evaluating claims from multiple perspectives.
Phenomenon / Hook
“Over 70 countries have banned germline editing of human embryos for reproductive purposes — including China, Germany, France, Canada, and India (Baylis et al., 2020, The CRISPR Journal). But in 2023, the UK approved mitochondrial replacement therapy — a form of genetic modification. The line between ‘acceptable’ and ‘unacceptable’ keeps shifting. Today, you draw the line.”
Source: Baylis, F. et al. (2020). “Human Germline and Heritable Genome Editing: The Global Policy Landscape.” The CRISPR Journal, 3(5). Open Access.
Materials
- Debate preparation handout (argument builder with claim-evidence-reasoning structure)
- Evidence packets: [[handouts/debate-evidence-packets]] (4–5 evidence strips per debate topic, pre-cut)
- Scoring rubric (peer evaluation — see below)
- Chart paper for argument mapping
- Timer
Bridge from L04
Homework (assigned at end of L04): Students read ONE of the evidence packets assigned to their debate topic. They must come to L05 with:
- At least one piece of evidence they find compelling (written on a notecard)
- One counterargument they anticipate from the other side
This ensures students arrive with material ready — the debate can start immediately.
Agenda
Opening (5 min)
- Review: What did we learn in L01–L04? (CRISPR mechanism, mutations, applications, ethics)
- Introduce the debate format: Philosophical Chairs (structured, respectful, evidence-based)
- Set norms:
- Speak to ideas, not people
- Use evidence from our lessons or the evidence packets
- Change your seat if your mind changes (that’s the point)
Explore & Debate (25 min)
Format: Philosophical Chairs (2 rounds)
-
Round 1 (12 min): “Germline gene editing of human embryos should be permitted for medical purposes.”
- Students physically move to AGREE / DISAGREE / UNDECIDED sides of the room
- Each side gets 2 minutes to build their argument (small group)
- Alternating speakers (2 min per side, 2 rounds)
- Students may switch sides at any time by moving their chair
-
Round 2 (13 min): “Parents should be allowed to select non-medical traits (height, eye color, intelligence) for their children through gene editing.”
- Same format
- Emphasis: Use different evidence than Round 1
During debates, teacher captures key arguments on chart paper:
| AGREE | DISAGREE |
|---|---|
| [Student arguments + evidence] | [Student arguments + evidence] |
Explain (8 min)
- Post-debate reflection:
- How many people changed sides? What changed your mind?
- What evidence was most compelling?
- What arguments did we NOT consider?
- Teacher synthesis: There is no consensus in science on germline editing. Key frameworks:
- Precautionary principle: Don’t act until you’re sure it’s safe
- Utilitarian view: Maximize benefit for the most people
- Rights-based view: Individuals have rights over their own genome
- Equity concern: Will gene editing widen the gap between rich and poor?
Elaborate (7 min)
- Individual Reflection (written):
- “Where do YOU draw the line? Write a 5-sentence paragraph defending your position with at least 2 pieces of evidence from this module.”
- This is the start of the transfer task draft.
Closing (5 min)
- Exit Ticket: [[exit-tickets/L05-exit-ticket]]
- Name one argument from the debate that changed or challenged your thinking.
- What is one unresolved question about gene editing that science hasn’t answered yet?
Differentiation
| Support | Extension |
|---|---|
| Provide sentence starters for the debate: “I agree/disagree because…” / “The evidence shows…” / “However, we should consider…” | Students write a rebuttal to the opposing side’s strongest argument |
| Allow students to be “journalists” who record arguments instead of debating | Research: What regulations currently exist for gene editing in the US? In other countries? |
Assessment
- Formative: Monitor debate participation and evidence use
- Summative (start of transfer task): Individual written reflection paragraph
- Exit Ticket: Metacognitive reflection on the debate
Teacher Notes
- Philosophical Chairs works best with clear norms. If your class hasn’t done this format before, model it briefly with a low-stakes question first (e.g., “Pineapple belongs on pizza”).
- The Round 2 prompt (non-medical traits) is intentionally harder. This is where the real thinking happens.
- If debates get heated, redirect to evidence: “What evidence supports that claim?”
- Collect the individual reflections — they serve as a draft for the transfer task.
- Announce the Pick Your Path transfer task options and due date in the closing.