1. Pair
What does heterozygous Aa mean?
Help beside the question
Read or point first. Compare the two alleles.
Answer guidance
The two alleles differ.
LAUNCH · GCSE BIOLOGY FOUNDATION · W13 · LESSON 2 · Aut2·W5
Punnett squares: construct the prediction
Learning objective
Construct a monohybrid Punnett square and explain how gametes combine to predict offspring genotypes.
40 minutes · one route · start from what you show today. Point, speak, sign, draw, write or direct an adult. An adult may read or scribe your exact words. Choose one route; do not complete all three.
4 MINUTES
Four clues to start
Supported · 4 questions
2. Gamete
How many alleles for this gene go in one gamete?
Help beside the question
Read or point first. One parent contributes one to the offspring pair.
Answer guidance
One.
3. Options
Which gamete alleles can an Aa parent produce?
Help beside the question
Read or point first. Separate the pair, not copy Aa into every margin.
Answer guidance
A or a.
4. Combine
A gamete with A combines with a gamete with a. What is the offspring genotype?
Help beside the question
Read or point first. Use one allele from each.
Answer guidance
Aa.
Standard · 4 questions
1. Pair
What does heterozygous Aa mean?
Help beside the question
Compare the two alleles.
Answer guidance
The two alleles differ.
2. Gamete
How many alleles for this gene go in one gamete?
Help beside the question
One parent contributes one to the offspring pair.
Answer guidance
One.
3. Options
Which gamete alleles can an Aa parent produce?
Help beside the question
Separate the pair, not copy Aa into every margin.
Answer guidance
A or a.
4. Combine
A gamete with A combines with a gamete with a. What is the offspring genotype?
Help beside the question
Use one allele from each.
Answer guidance
Aa.
Stretch · 4 questions
1. Pair
What does heterozygous Aa mean?
Help beside the question
Compare the two alleles.
Answer guidance
The two alleles differ.
2. Gamete
How many alleles for this gene go in one gamete?
Help beside the question
One parent contributes one to the offspring pair.
Answer guidance
One.
3. Options
Which gamete alleles can an Aa parent produce?
Help beside the question
Separate the pair, not copy Aa into every margin.
Answer guidance
A or a.
4. Combine
A gamete with A combines with a gamete with a. What is the offspring genotype? Give a reason.
Help beside the question
Use one allele from each.
Answer guidance
Aa. Accept a scientifically correct reason that uses the relevant model or evidence.
Feedback loop
SPACE
VOICE · What does heterozygous Aa mean?
AUDIENCE
INFLUENCE
SPACE available · VOICE waiting · AUDIENCE waiting · INFLUENCE waiting
Say or show your answer here: What does heterozygous Aa mean? In-lesson edit; structured verbal response; for full essays, deferred edit.
At Four clues to start, an adult receives it and names back what they heard, in your words. R goes on only after that.
Not yet / needs help → reduce the prompt: take the first step of “What does heterozygous Aa mean” with the smallest prompt that works, then wait.
Did it with support → same task, new example: “What does heterozygous Aa mean” again with a fresh example and one prompt fewer.
Did it independently → explain a reason: ask why for “What does heterozygous Aa mean” and take the reason in the pupil’s own mode.
Did it and explained → move on: Choose a first idea
SPACE stays available. VOICE is received. AUDIENCE names back exactly. INFLUENCE changes one real next action.
Feedback codes (staff): VF Verbal feedback given here · WS Worked with support · I Independent · NS + Next step — one specific thing · E Evidence on Earwig · R Responded — loop closed · // Self-edit point · ? Read this back to me
Space — the conditions that make response possible:
- Regulation first. A dysregulated student cannot respond to feedback. Co-regulation, sensory tools and time take priority over the technical content of the feedback.
- No public comparison. No grade boards, no "look how X has improved."
- Permission to refuse. A student who declines to respond today is not punished — refusal is information.
Feedback & Marking Policy 2025/2026 (Pilot), Issue 1 — body sections 5, 11, 12 and 13, quoted.
LAUNCH · GCSE BIOLOGY FOUNDATION · W13 · LESSON 2 · 4 MINUTES
Choose a first idea
What belongs outside a Punnett square?
Think or discuss first. No answer chosen yet.
Feedback loop
SPACE
VOICE · Think or discuss first.
AUDIENCE
INFLUENCE
SPACE available · VOICE waiting · AUDIENCE waiting · INFLUENCE waiting
Say or show your answer here: Think or discuss first. In-lesson edit; structured verbal response; for full essays, deferred edit.
At Choose a first idea, an adult receives it and names back what they heard, in your words. R goes on only after that.
Not yet / needs help → reduce the prompt: take the first step of “Think or discuss first” with the smallest prompt that works, then wait.
Did it with support → same task, new example: “Think or discuss first” again with a fresh example and one prompt fewer.
Did it independently → explain a reason: ask why for “Think or discuss first” and take the reason in the pupil’s own mode.
Did it and explained → move on: Watch the model
SPACE stays available. VOICE is received. AUDIENCE names back exactly. INFLUENCE changes one real next action.
Feedback codes (staff): VF Verbal feedback given here · WS Worked with support · I Independent · NS + Next step — one specific thing · E Evidence on Earwig · R Responded — loop closed · // Self-edit point · ? Read this back to me
Space — the conditions that make response possible:
- Regulation first. A dysregulated student cannot respond to feedback. Co-regulation, sensory tools and time take priority over the technical content of the feedback.
- No public comparison. No grade boards, no "look how X has improved."
- Permission to refuse. A student who declines to respond today is not punished — refusal is information.
Feedback & Marking Policy 2025/2026 (Pilot), Issue 1 — body sections 5, 11, 12 and 13, quoted.
LAUNCH · GCSE BIOLOGY FOUNDATION · W13 · LESSON 2 · 5 MINUTES
Watch the model
For this one-gene, complete-dominance model, both parents are heterozygous: Aa × Aa.
Worked explanation · reveal after thinking
This is a simple monohybrid complete-dominance model. Dominant does not mean common, stronger, healthier or better. Treat each fertilisation as an independent event. Avoid deterministic single-gene examples such as eye colour or tongue rolling.
32-second silent captioned explainer · optional
No sound or autoplay. Use instead of part of the modelling time, not as an extra activity.
Full transcript
Describe the parents. For this one-gene, complete-dominance model, both parents are heterozygous: Aa × Aa.
Separate into gametes. Each parent can produce gametes carrying A or a. Put one allele in each margin box.
Combine one from each. Each offspring box combines one allele from the top with one from the side: AA, Aa, Aa and aa.
Read the probability. The chance of aa is one out of four, or 25%, for each fertilisation. Four offspring do not have to follow this pattern.
LAUNCH · GCSE BIOLOGY FOUNDATION · W13 · LESSON 2 · 5 MINUTES
Sort using the evidence
Choose a card, then choose a group. Explain one placement using its clue.
Drag, or use Tab and Enter to select a card and its group. Pointing or adult-directed placement works too.
Possible gamete
Possible offspring genotype
Notation error
Choose a card first.
Read the card clues
A: One allele can be carried by one gamete.
a: This is the alternative gamete allele.
AA: Two A gametes can combine.
Aa: One A and one a combine.
aa: Two a gametes can combine.
Aa in one gamete box: A gamete has one allele for this gene, not the pair.
Would a small change help? · optional
Ask the lesson teacher for clearer labels, fewer cards, reading help, an adult-directed model or more thinking time. Your teacher will explain what can change, try it and check its effect. Ask privately or pass; no extra form is needed.
Group explanations · reveal after sorting
A → Possible gamete. One allele can be carried by one gamete.
a → Possible gamete. This is the alternative gamete allele.
AA → Possible offspring genotype. Two A gametes can combine.
Aa → Possible offspring genotype. One A and one a combine.
aa → Possible offspring genotype. Two a gametes can combine.
Aa in one gamete box → Notation error. A gamete has one allele for this gene, not the pair.
Feedback loop
SPACE
VOICE · Choose a card, then choose a group.
AUDIENCE
INFLUENCE
SPACE available · VOICE waiting · AUDIENCE waiting · INFLUENCE waiting
Say or show your answer here: Choose a card, then choose a group. In-lesson edit; structured verbal response; for full essays, deferred edit.
At Sort using the evidence, an adult receives it and names back what they heard, in your words. R goes on only after that.
Not yet / needs help → reduce the prompt: take the first step of “Choose a card, then choose a group” with the smallest prompt that works, then wait.
Did it with support → same task, new example: “Choose a card, then choose a group” again with a fresh example and one prompt fewer.
Did it independently → explain a reason: ask why for “Choose a card, then choose a group” and take the reason in the pupil’s own mode.
Did it and explained → move on: Work through one example
SPACE stays available. VOICE is received. AUDIENCE names back exactly. INFLUENCE changes one real next action.
Feedback codes (staff): VF Verbal feedback given here · WS Worked with support · I Independent · NS + Next step — one specific thing · E Evidence on Earwig · R Responded — loop closed · // Self-edit point · ? Read this back to me
Space — the conditions that make response possible:
- Regulation first. A dysregulated student cannot respond to feedback. Co-regulation, sensory tools and time take priority over the technical content of the feedback.
- No public comparison. No grade boards, no "look how X has improved."
- Permission to refuse. A student who declines to respond today is not punished — refusal is information.
Feedback & Marking Policy 2025/2026 (Pilot), Issue 1 — body sections 5, 11, 12 and 13, quoted.
LAUNCH · GCSE BIOLOGY FOUNDATION · W13 · LESSON 2 · 4 MINUTES
Work through one example
Worked example
Construct BB × bb in a simple one-gene model.
Step 1
A BB parent can contribute only B gametes.
Step 2
A bb parent can contribute only b gametes.
Step 3
Combine one from each: every predicted offspring is Bb.
Step 4
The predicted chance of Bb is 100% under these model assumptions.
LAUNCH · GCSE BIOLOGY FOUNDATION · W13 · LESSON 2 · 4 MINUTES
Build the cross, then check the chance
Complete the four boxes for Aa × Aa. Use one allele from each margin. Then change the second parent to aa and compare the two crosses.
| Cross | Parent 1 gametes | Parent 2 gametes |
|---|---|---|
| Aa × Aa | A or a | A or a |
| Aa × aa | A or a | a only |
Build a Punnett square
Choose a cross, fill every offspring box, then check. The square predicts a chance for each fertilisation, not a family schedule.
| Gametes | A | a |
|---|---|---|
| A | ||
| a |
Fill the four boxes. Each uses one allele from each parent.
Worked explanation · reveal after thinking
Aa × Aa gives AA, Aa, Aa, aa: aa probability 1/4. Aa × aa gives Aa, Aa, aa, aa in an equally weighted 2×2 representation: aa probability 1/2.
Feedback loop
SPACE
VOICE · Complete the four boxes for Aa × Aa.
AUDIENCE
INFLUENCE
SPACE available · VOICE waiting · AUDIENCE waiting · INFLUENCE waiting
Say or show your answer here: Complete the four boxes for Aa × Aa. In-lesson edit; structured verbal response; for full essays, deferred edit.
At Build the cross, then check th, an adult receives it and names back what they heard, in your words. R goes on only after that.
Not yet / needs help → reduce the prompt: take the first step of “Complete the four boxes for Aa × Aa” with the smallest prompt that works, then wait.
Did it with support → same task, new example: “Complete the four boxes for Aa × Aa” again with a fresh example and one prompt fewer.
Did it independently → explain a reason: ask why for “Complete the four boxes for Aa × Aa” and take the reason in the pupil’s own mode.
Did it and explained → move on: Show your understanding
SPACE stays available. VOICE is received. AUDIENCE names back exactly. INFLUENCE changes one real next action.
Feedback codes (staff): VF Verbal feedback given here · WS Worked with support · I Independent · NS + Next step — one specific thing · E Evidence on Earwig · R Responded — loop closed · // Self-edit point · ? Read this back to me
Space — the conditions that make response possible:
- Regulation first. A dysregulated student cannot respond to feedback. Co-regulation, sensory tools and time take priority over the technical content of the feedback.
- No public comparison. No grade boards, no "look how X has improved."
- Permission to refuse. A student who declines to respond today is not punished — refusal is information.
Feedback & Marking Policy 2025/2026 (Pilot), Issue 1 — body sections 5, 11, 12 and 13, quoted.
LAUNCH · GCSE BIOLOGY FOUNDATION · W13 · LESSON 2 · 10 MINUTES
Show your understanding
Supported · choose one route
1. Construct
Complete Aa × Aa with labelled gametes and four offspring boxes.
Write parents first. Put one allele in each margin. Fill each box from its column and row.
2. Compare
Construct Aa × aa and state the chance of aa.
Count matching boxes ___ out of four. Divide by four and multiply by 100 to give the percentage.
3. Explain
Why do two boxes sometimes contain the same genotype?
Trace the column and row for each matching box. Different gamete combinations can give the same allele pair.
Standard · choose one route
1. Construct
Complete Aa × Aa with labelled gametes and four offspring boxes.
Combine one letter from the top and one from the side.
2. Compare
Construct Aa × aa and state the chance of aa.
The aa parent contributes only a.
3. Explain
Why do two boxes sometimes contain the same genotype?
Different gamete combinations can give the same pair.
Stretch · choose one route
1. Construct
Complete Aa × Aa with labelled gametes and four offspring boxes.
Combine one letter from the top and one from the side.
2. Compare
Construct Aa × aa and state the chance of aa.
The aa parent contributes only a.
3. Critique a square
A pupil places AA and aa in the margins of Aa × Aa. Explain and repair the error.
The margins contain gametes, not diploid offspring.
Feedback loop
SPACE
VOICE · Complete Aa × Aa with labelled gametes…
AUDIENCE
INFLUENCE
SPACE available · VOICE waiting · AUDIENCE waiting · INFLUENCE waiting
Say or show your answer here: Complete Aa × Aa with labelled gametes and four offspring boxes. In-lesson edit; structured verbal response; for full essays, deferred edit.
At Show your understanding, an adult receives it and names back what they heard, in your words. R goes on only after that.
Not yet / needs help → reduce the prompt: take the first step of “Complete Aa × Aa with labelled gametes and four offspring boxes” with the smallest prompt that works, then wait.
Did it with support → same task, new example: “Complete Aa × Aa with labelled gametes and four offspring boxes” again with a fresh example and one prompt fewer.
Did it independently → explain a reason: ask why for “Complete Aa × Aa with labelled gametes and four offspring boxes” and take the reason in the pupil’s own mode.
Did it and explained → move on: Two small checks
SPACE stays available. VOICE is received. AUDIENCE names back exactly. INFLUENCE changes one real next action.
Feedback codes (staff): VF Verbal feedback given here · WS Worked with support · I Independent · NS + Next step — one specific thing · E Evidence on Earwig · R Responded — loop closed · // Self-edit point · ? Read this back to me
Space — the conditions that make response possible:
- Regulation first. A dysregulated student cannot respond to feedback. Co-regulation, sensory tools and time take priority over the technical content of the feedback.
- No public comparison. No grade boards, no "look how X has improved."
- Permission to refuse. A student who declines to respond today is not punished — refusal is information.
Feedback & Marking Policy 2025/2026 (Pilot), Issue 1 — body sections 5, 11, 12 and 13, quoted.
LAUNCH · GCSE BIOLOGY FOUNDATION · W13 · LESSON 2 · 4 MINUTES
Two small checks
Supported · 2 questions
1. Construct
For Aa × Aa, list the four predicted genotype boxes.
Help beside the question
Use: my answer is ___ because ___. Point to a model or card first. Combine the row and column labels.
Answer guidance
AA, Aa, Aa, aa.
2. Interpret
What fraction of boxes is heterozygous?
Help beside the question
Use: my answer is ___ because ___. Point to a model or card first. Count Aa, including the equivalent aA combination.
Answer guidance
2/4 = 1/2.
Standard · 2 questions
1. Construct
For Aa × Aa, list the four predicted genotype boxes.
Help beside the question
Combine the row and column labels.
Answer guidance
AA, Aa, Aa, aa.
2. Interpret
What fraction of boxes is heterozygous?
Help beside the question
Count Aa, including the equivalent aA combination.
Answer guidance
2/4 = 1/2.
Stretch · 2 questions
1. Construct
For Aa × Aa, list the four predicted genotype boxes.
Help beside the question
Combine the row and column labels.
Answer guidance
AA, Aa, Aa, aa.
2. Critique a square
A pupil places AA and aa in the margins of Aa × Aa. Explain and repair the error.
Help beside the question
The margins contain gametes, not diploid offspring.
Answer guidance
An Aa parent makes gametes with A or a. Put A and a in each margin, then combine to make diploid offspring genotypes.
Keep one useful science explanation. No additional participation record is required.
Feedback loop
SPACE
VOICE · For Aa × Aa, list the four predicted…
AUDIENCE
INFLUENCE
SPACE available · VOICE waiting · AUDIENCE waiting · INFLUENCE waiting
Say or show your answer here: For Aa × Aa, list the four predicted genotype boxes. In-lesson edit; structured verbal response; for full essays, deferred edit.
At Two small checks, an adult receives it and names back what they heard, in your words. R goes on only after that.
Not yet / needs help → reduce the prompt: take the first step of “For Aa × Aa, list the four predicted genotype boxes” with the smallest prompt that works, then wait.
Did it with support → same task, new example: “For Aa × Aa, list the four predicted genotype boxes” again with a fresh example and one prompt fewer.
Did it independently → explain a reason: ask why for “For Aa × Aa, list the four predicted genotype boxes” and take the reason in the pupil’s own mode.
Did it and explained → move on: Two small checks
SPACE stays available. VOICE is received. AUDIENCE names back exactly. INFLUENCE changes one real next action.
Feedback codes (staff): VF Verbal feedback given here · WS Worked with support · I Independent · NS + Next step — one specific thing · E Evidence on Earwig · R Responded — loop closed · // Self-edit point · ? Read this back to me
Space — the conditions that make response possible:
- Regulation first. A dysregulated student cannot respond to feedback. Co-regulation, sensory tools and time take priority over the technical content of the feedback.
- No public comparison. No grade boards, no "look how X has improved."
- Permission to refuse. A student who declines to respond today is not punished — refusal is information.
Earwig, lean capture (E): 30-second clip, photo, or one-line context note. Central tags only. Listen / look before tagging (Audience).
Feedback & Marking Policy 2025/2026 (Pilot), Issue 1 — body sections 5, 11, 12 and 13, quoted.