Verbatim SoW objective: Complete a genetic cross (digital Punnett square).
Arrival
Look at this week’s letter tiles A and a. Point to one detail you notice.
Offer a private, predictable start. Do not require previous knowledge.
Starter
Recall three ideas from earlier lessons. Show one answer at a time.
- What is a gene?
- What do stem cells do in growth?
- Where are chromosomes found in an animal cell?
Today I can:
- I can pair one allele from each parent.
- I can find the aa chance in four squares.
- I can evaluate why probability does not guarantee an exact count.
All pupils respond; reveal the answers only after attempts. Revisit success criteria.
I do
Watch the full model. Point to the step that answers today’s question.
Words
| Word | Meaning | Example |
|---|---|---|
| allele | a version of a gene | A and a represent two alleles in our invented model. |
| genotype | the pair of alleles shown by letters | Aa is one possible genotype in this model. |
| dominant | an allele shown by one copy in this simple model | A is dominant in our invented flower model. |
| recessive | an allele shown when two copies are present in this model | aa shows the recessive version in our model. |
| Punnett square | a grid that shows possible allele pairs | The Punnett square for Aa × aa has four cells. |
Full model: Place A/a atop the grid for one parent; place a/a at its side for the other. Pair one allele from each edge: Aa, aa, Aa, aa. Two of four boxes are aa: a 1 in 2 chance per offspring, not an exact family count.
Show me: Show me: which allele can the aa parent pass on?
Answer: Only a.
Model one complete example; check every pupil’s response to the show-me question.
We do
Complete the missing step in the part-done model. Speak, then match the cards.
One-minute reset: use the agreed move, then return to one step.
Part-done model: Aa × aa: top A, a; side a, a. First row Aa, aa; second row ___, ___. Chance of aa: ___ out of 4.
Speak first: One allele from the top is …; one from the side is …; together they make …
F · support: Place one letter tile from the top and one from the side into a single square. Point to the next pair.
M · explain: Explain why the two aa squares represent half the model outcomes.
H · stretch: Predict the aa chance for Aa × Aa before checking a second model. Explain the change.
Complete the 2 × 2 digital grid. Choose the genotype in each square.
Ready to match.
Wait five seconds, gesture, then cue if needed. Support the route without supplying the missing answer.
We do 2
Choose one hinge answer. Show it at the same time as the group.
All-pupil hinge: New cross: Aa × Aa. What is the chance of aa for each offspring?
Show one answer to the adult at the same time as everyone else. Point or use a card, too. Then explain to a partner.
Collect simultaneous responses, apply the decision rule and parallel hinge in the staff note.
Independent
Calculate the aa probability for Aa × aa. Evaluate an exact-count claim about real offspring.
One-minute reset: use the agreed move, then return to one step.
Talk before write: The chance is … because …; this does not promise …
You can plan in any language.
F: Complete Aa × aa with allele tiles. Top ___ and side ___ make ___.
M: Calculate and justify the aa probability from the grid. I count ___ aa squares out of four, so …
H: Evaluate an exact-count claim about four real offspring. The grid shows a chance, not a promise, because …
Go deeper: Compare aa chances for Aa × Aa and Aa × aa with a second grid.
Early-finisher stretch — Faulty headings audit: Correct a faulty grid that gives an Aa parent two A headings; explain its wrong probability.
Show it your way: point, sign, speak, draw, type, write, use a scribe or a staff-captured photo.
At lesson start choose one adult with supported pupils and one holding the group; swap during the week. Record independence and prompt level.
Try it with kit · prepared model
Kit: Large A and a letter tiles, prepared Punnett grid, tray
- Place one prepared tile from each parent into each grid square.
Risk: Small loose letter tiles could be mouthed or fall.
Safe: Use large tiles on a tray. Keep them out of mouths and collect them after.
Check the school risk assessment and exact prepared kit. This is optional model rehearsal, not a claimed core practical.
Review
Tell a partner what you changed after feedback. Mark a real edit // and read it back when asked ?.
One-minute reset: use the agreed move, then return to one step.
My feedback was … Name the actual point an adult or partner noticed. Make one true self-edit //. Ask “Read this back to me” ? if that helps.
Give a precise VF or NS(+) only when it actually happens. Invite a true self-edit and read-back.
Exit
Show what you know with a model and explain one reason.
Check today’s success:
- I can pair one allele from each parent.
- I can find the aa chance in four squares.
- I can evaluate why probability does not guarantee an exact count.
What am I learning? I am learning to calculate genetic probability with a Punnett square and evaluate its limits.
My feedback was … Name what you heard at Review.
Next I need to … Check the top and side alleles before giving a chance.
How I know: I can fill Aa × aa and explain that two of four model squares are aa, with no promise about real offspring.
Your teacher hears your answer and uses it to choose our next model, prompt or example.
Hear the answer privately in a valid mode and use it to change the next example or prompt.