Authentic Lessons for 21st Century Learning

A Trait Accompli: An Introduction to Mendelian Genetics

Mendelian Genetics

K20 Center, Shelly Pratt | Published: May 25th, 2022 by K20 Center

  • Grade Level Grade Level 9th, 10th, 11th, 12th
  • Subject Subject Science
  • Course Course Biology I
  • Time Frame Time Frame 4-5 class period(s)
  • Duration More 200 minutes


Students will conduct a data-driven lab using common human phenotypes and present their findings to their peers in a Gallery Walk. Common genetic vocabulary will be researched by students and they will present their findings to the class. Students will connect common genetic themes with their earlier research on human phenotypes to draw conclusions about why organisms look the way they do.

Essential Question(s)

Why do organisms look the way they do?



Students will watch two short video clips about dominant and recessive genetic traits.


Students will conduct a phenotypic analysis lab of 13 common human characteristics using information collected from the class, including gender data.


Students will make calculations based on data from a lab and answer accompanying questions. They will explain their results in a Gallery Walk presentation.


Students will conduct Internet research on basic genetic terms/concepts. They will relate the terms to everyday examples and specifically to traits for which they collected data during the lab. They will then put the information into a PowerPoint presentation or Google Slides.


Students will present their research to the class using a slideshow or PowerPoint. Students not presenting will take notes for their notebooks for later reference. Teachers should add/subtract information as needed on particular areas.


  • YouTube Video clip 1 (2 min): "Are Your Traits Dominant?"

  • YouTube Video clip 2 (2 min): "How Special are Your Traits?"

  • Overhead projector

  • Laptop with "Lab, Part B" PowerPoint loaded and ready to project

  • Lab, Part A handout with data table (attached)

  • Genetic test strips for the tastes of PTC, thiourea, and sodium benzoate

  • Completed data table for each student

  • Poster Project Student Handout (attached; one per group)

  • 2 sheets of graph paper per group

  • Colored pencils for each group

  • Scissors for each group

  • Colored markers for each group

  • Glue sticks or tape for each group

  • Poster paper for each group

  • Chromebook, laptop, or computer with Internet access for each person

  • Research Assignment handout (attached; one per group)

  • Research Slideshow Template (attached)

  • Notebooks for each person


Pair students using the Appointment Clock Strategy. These pairs will also be kept together for the Explore portion of the lesson. Students will watch the two-minute video clip "Are Your Traits Dominant?" They will then watch a second two-minute video clip called "How Special Are Your Physical Traits?" These videos will introduce the Explore portion of the lesson.


Keep students in the same pairs as determined earlier in the lesson by the Appointment Clock. Each student should receive the "A Trait Accompli Lab, Part A" handout. The handout includes instructions for understanding traits that have been grouped as type A or type B along with a data table. Teachers should use the attached PowerPoint, "A Trait Accompli Lab, Part B," to present students with the essential question, which should be revisited several times throughout the lesson. The teacher should present each phenotypic trait in the slideshow, starting with earlobe attachment and ending with sodium benzoate taster. Teachers should pause between each trait and have students identify their phenotype and genotype possibilities. Partners will help each other decide their phenotypes as each trait is presented. Teachers should make a count of how many students have each trait type, A or B, and also record how many students of each gender have each trait type. It should take only about three minutes to cover each trait, with this activity taking about 40-45 minutes.


Student pairs will calculate the data from the Explore portion of the lesson. Once all data is collected, students will begin calculating percentages for the traits of the class and for the traits separated out by gender. Student pairs will graph the data and use it to answer a set of analysis questions. Directions for the graphing and questions to be answered are included in the handout "A Trait Accompli, Part A." Results will be presented on poster paper and students will use a Gallery Walk to present their findings. Students will look over the findings of the other pairs to see if they are similar, and add one comment to the essential question at the bottom of each poster presentation. This portion of the activity should take approximately 50 to 75 minutes.


The teacher should pair students with new partners using the Appointment Clock strategy and assign each pair to a research group. Use the attached Research Assignment handout which provides group numbers and research topics. The teacher can make available the attached Research Slideshow Template to students, or the pairs can create their own slides from scratch, using the information provided in the "Research Assignment Handout." Each pair will create one slideshow containing four slides. This portion of the lesson will last approximately 25-30 minutes.


Students will present the research to the class on an overhead, proceeding consecutively, with all pairs assigned topic one presenting first, followed by those working on research topic two, and continuing until all students have presented. Students will take notes on the information presented and ask questions as the lesson progresses. The "Research Assignment Handout" provides a template of the slideshow expectations alongside an example of how student notes might start and end with the essential question. Students will use their research to expand on past knowledge and answer the essential question. This portion of the lesson will take approximately 50 minutes.