Codominant Inheritance – Genetics Lesson with Punnett Squares (PowerPoint)

This comprehensive PowerPoint lesson introduces students to codominant inheritance through clear explanation, real-world examples, and guided Punnett square practice.

The lesson builds from prior knowledge of dominant and recessive traits and shows how codominance differs, using familiar contexts such as cattle coat colour (roan), human ABO blood groups, flowers, and tortoiseshell cats. Concepts are reinforced through frequent Think-Pair-Share prompts, true/false checks, multiple-choice questions, and fully modelled genetic crosses.

Students are explicitly taught how to write codominant genotypes correctly, including the use of superscripts and multiple alleles, and how to interpret both genotype and phenotype ratios.

Learning Objectives

Explain what codominance means in genetics

Distinguish between dominance and codominance

Use correct genotype notation for codominant traits

Complete Punnett squares for codominant inheritance

Interpret genotype and phenotype ratios

Apply codominance to real biological examples

What’s Included

Editable PowerPoint lesson

Clear explanation of codominance vs dominance

Real-world examples (cattle, flowers, blood groups, cats)

Multiple-allele inheritance (ABO blood types)

Genotype notation using superscripts

Think-Pair-Share discussion questions

True/false and MCQ concept checks

Step-by-step codominant Punnett squares

Sex-linked codominance example (tortoiseshell cats)

Exit ticket for student self-assessment

Suitable For

KS3 Science

KS4 / GCSE Biology (Inheritance & Variation)

Secondary genetics units

Whole-class teaching or revision

Format

PowerPoint (fully editable)

TES Notes

This lesson works particularly well after simple Mendelian inheritance and before assessment tasks on inheritance patterns. It is suitable for a full lesson or extended sequence depending on pace.