Students analyze real pedigree charts to determine inheritance patterns using evidence.

This interactive lesson develops student skill in interpreting pedigree charts by focusing on three inheritance patterns: dominant traits, recessive traits, and sex-linked recessive traits. All examples use real human conditions so students can connect abstract patterns to biological reality.

Students begin by examining three modeled traits:

• ectrodactyly (dominant)

• albinism (recessive)

• color blindness (sex-linked recessive)

For each case, students mark key features directly on the pedigree to identify visual clues associated with each inheritance pattern. This process establishes a systematic method for analyzing pedigrees rather than relying on guesswork.

Students then:

• complete a chart of diagnostic clues for each inheritance type

• compare how different patterns appear across generations

• practice applying these rules to new pedigrees

In the application phase, students analyze six additional pedigree charts showing different human traits and determine the most likely inheritance pattern for each case.

The lesson emphasizes:

• recognition of generational patterns

• use of evidence from family data

• distinction between autosomal and sex-linked inheritance

• structured reasoning about genotype and phenotype

This lesson is designed to support:

• mastery of pedigree interpretation

• understanding of inheritance mechanisms

• application of genetics concepts to real cases

• preparation for more advanced genetic analysis

It functions well as:

• a core lesson on pedigrees

• a guided practice activity

• or a reinforcement lesson within a heredity unit

Grade & Course Recommendation:

• Middle School: Advanced Grade 8 life science course with prior exposure to Punnett squares.

• High School: Core Grade 9–11 biology genetics unit resource.

To preview this lesson, click here.

Cross-Curricular Connections:

• Math Integration: Probability calculations for inheritance patterns.

• ELA Integration: Constructing explanations and defending claims using data.

• History of Science: Introduce Mendel’s work as foundational context.

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NGSS (Next Generation Science Standards)

• HS-LS3-1: Ask questions to clarify relationships about the role of DNA and chromosomes in coding the instructions for characteristic traits passed from parents to offspring.

• HS-LS3-2: Make and defend a claim based on evidence that inheritable genetic variations may result from new genetic combinations through meiosis, errors during replication, and/or mutations caused by environmental factors. (connection: using pedigree charts to identify inheritance mechanisms and genetic variations)

• HS-LS3-3: Apply concepts of statistics and probability to explain the variation and distribution of expressed traits in a population. (connection: interpreting patterns of inheritance, dominant/recessive traits, and carrier frequencies)

• Science & Engineering Practices: Analyzing and interpreting data; Constructing explanations; Engaging in argument from evidence.

• Crosscutting Concepts: Cause and effect; Patterns; Structure and function.

Common Core Standards

• CCSS.ELA-LITERACY.RST.9-10.4: Determine the meaning of domain-specific vocabulary relevant to genetics and heredity.

• CCSS.ELA-LITERACY.RST.9-10.7: Integrate quantitative or technical information expressed in words with visual data (e.g., combining textual clues with chart analysis to infer inheritance mode).

• CCSS.ELA-LITERACY.WHST.9-10.2: Write informative/explanatory texts to convey complex scientific ideas clearly and accurately (e.g., summarizing evidence for a particular inheritance pattern).