Heredity & Traits - Intro

Inheritance and variation of traits (simple model, with caveats)

            📚 Science
                            🎓 Grade 7
                                        ⏱️ 10 minutes
                    

Learning Objectives

Define heredity, trait, gene, and allele, and distinguish genotype from phenotype in a simple model.
Use a 2x2 Punnett square to predict possible offspring genotypes and connect sexual reproduction to increased variation.

            Progress
            6 sections
        

1
Engage
                            ~1 minutes                        

Engage (1 minute)

Teacher says: "Two siblings can look different even with the same parents. Why?"

Students do a 10-second pair-share. Then: "Today we start heredity: how traits can be passed on, and why variation happens."

2
Vocabulary + caution
                            ~2 minutes                        

                📖
                Key vocabulary (fast, student-friendly)            

Heredity: passing traits from parents to offspring. Trait: a characteristic (for example, flower color). Gene: a segment of DNA that influences a trait. Allele: a version of a gene. Genotype: the alleles an organism has. Phenotype: what you can observe (appearance or measurable trait).

                ⚠️
                Reality check (avoid a common trap)            

In this intro we use a simple 1-gene, 2-allele model to learn the tool (Punnett squares). In real life, many traits involve multiple genes and environment.

3
Punnett square visual + key ideas
                            ~3 minutes                        

Punnett square example (fictional critter)

                Cross: Aa x Aa (fictional trait)Parent 1 allelesParent 2 allelesAaAaAAAaAaaa            
A 2 by 2 Punnett square for a fictional trait. One parent provides alleles A and a across the top. The other parent provides alleles A and a down the left side. The four boxes show AA, Aa, Aa, and aa....

Explain (2 minutes): what students must remember today

Offspring inherit one allele for a gene from each parent.
Sexual reproduction mixes alleles, increasing variation.
A Punnett square lists possible allele combinations, not guarantees.

4
Activity: allele draw
                            ~2 minutes                        

5
Quick check
                            ~1 minutes                        

Question 1

Which definition best matches heredity?

The study of rocks and minerals
Passing traits from parents to offspring
A change in an organism caused only by exercise
The motion of planets around the Sun

Question 2

Sexual reproduction usually creates more variation among offspring than asexual reproduction.

Question 3

A(n) ______ is a version of a gene.

6
Exit ticket
                            ~1 minutes                        

Question 4

In 1-2 sentences: What does a Punnett square help you predict, and why are real offspring outcomes not always exactly those predictions?

Expected length: 20-60 words