03 Dominant & Recessive (with Punnett Squares)

👩‍🏫 Teacher’s Guide

Objective

Students will differentiate dominant and recessive alleles and use Punnett squares to predict possible offspring traits.

Vocabulary

dominant, recessive, allele, genotype, phenotype, probability

Teaching Notes

• Start with a picture, object, or quick demo to activate prior knowledge.
• Define key terms in context and model how to use them in sentences.
• Use quick checks (thumbs up/down, exit slips) to confirm understanding before practice.
• Encourage evidence‑based claims using observations, diagrams, or simple data tables.

🧒 Student Worksheet

Concept and Helping Material

Definition. In paired genes, a dominant allele masks a recessive allele. Punnett squares model probability of allele combinations and resulting traits.

Helping ideas and samples:

• Try a quick sort, draw‑and‑label, or compare‑and‑contrast.
• Name one place you see this idea in class or at home.
• Safety note if needed.

Vocabulary and Definition

• — an allele that masks another when present
• — an allele expressed only when two copies are present
• — a version of a gene
• — the allele combination of an organism
• — the observable trait
• — likelihood of an outcome

Words to Learn

e.g. , , , , ,

Sentences to Fill In

1. This topic connects to .

2. A gene is a of DNA that codes for a trait.

3. An organism’s visible traits are its .

4. The order of DNA bases is called the .

5. Two recessive alleles are needed to a recessive trait.

Hands-On Experiment or Activities

What You Need: simple classroom items (paper, markers, sticky notes, beans/counters).

What You Do: 1) observe, 2) record, 3) share.

Think and Talk: What changed?

What stayed the same?

Reflection

• What did you learn about this topic?
• Which vocabulary word was hardest, and how will you remember it?