Inheritance Patterns (#6 of 6): Pedigrees

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1. Students will apply concepts of statistics and probability to explain the variation and distribution of expressed traits in a population. (HS-LS-3) 2. Students will understand that cells store and use genetic information to guide their functions. An organism’s genotype determines its phenotype. These traits can be dominant or recessive depending on the alleles found on their genes.

Big Idea

Nearly all human traits, even many diseases, are inherited in predictable ways. Using the tools of mathematics and modeling, these inheritance patterns can be properly deduced.

Learner Goals

Note: I recommend that you first check out this resource in order to get the most out of this lesson!

In high school I took several drafting classes and, for a while, I had hoped to become an architect. With respect to planning instruction and teaching, I feel that I can still live out the detailed approach to building something intricate and complex even though the product is a lesson rather than a certain "built environment".

The lesson-planning document that I uploaded to this section is a comprehensive overview of how I approach lesson planning. This template includes the "Big Three" aspects of the NGSS standards: Disciplinary Core Ideas, Crosscutting Concepts, and Science Practices. Of course, there are many other worthy learning goals, skills, instructional strategies, and assessments that can be integrated into a class session. I don't feel compelled to check every box but, rather, use it as a guide to consider various options and tailor the lesson in light of these. Furthermore, for the bigger picture of this unit of study please refer to this document.

With regard to this particular lesson (as part of the series) students will be able to...

1. Explain how are traits passed from one generation to another and why do members of the same family have different traits.

2. Explain why some traits are hidden in one generation and expressed in the next.

3. Apply concepts of statistics and probability to explain the variation and distribution of expressed traits in a population. (HS-LS-3)

4. Solve monohybrid (one trait) and dihybrid (two trait) cross problems (AKA Punnett Squares).

a)    Complete dominance (click here to link to lesson)

b)    Incomplete dominance (click here to link to lesson)

c)    Co-dominance (e.g. ABO blood types) (click here to link to lesson)

d)    Sex-linked (e.g. colorblindness and hemophilia) (click here to link to lesson)

5. Interpret a pedigree and the symbols used to represent males, females, affected and unaffected individuals. (click here to link to lesson)

6. Make and defend a claim for the inheritance pattern(s) found in a given pedigree. (focus of this lesson)

I hope you get some value from my work!

Anticipatory Set ("Hook")

15 minutes

Teaching Challenge: How do I support my students to compose, communicate, and evaluate a clearly stated, evidence-based, compelling argument?

Pedigree CER- I adapted this Claim-Evidence-Reason (CER) template for use in today's lesson but it can be implemented in pretty much any case where you want students to make and defend an arugment (and the strategy certainly extends beyond science to ELA, Math, Social Studies, etc.).

Students will be randomly assigned one of three pedigrees (see Pedigree Patterns) . Using the information therein, students will...

1) describe the details of the pedigree and fill out Box I (Data).

2) make a claim ("what they know") regarding the inheritance pattern present in Box II (Claim)

3) Justify the chosen inheritance pattern with evidence ("how they know") in Box III

4) and reason through their thinking ("why the evidence supports their claim") in Box IV

What is at stake here is the teaching of critical thinking skills and habits of mind. Of using good reasoning and logic to support a claim. Of course, this extends well beyond science itself. Dare I say even political science has great need of such skills?

There is a hilarious little book titled An Illustrated Book of Bad Arguments by Ali Almossawi. In it, the major logical fallacies are described and a pithy and incredibly well done cartoon is included that illustrates each fallacy in action. I highly recommend checking it out!

Photo credit:

Instructional Input/Student Activities

35 minutes

The truth of the matter is that I am not only a teacher of science content and practices but also of reading, writing, math, etc. The more interconnections I can make with the disciplines of study, the more relevant (less isolated) my subject becomes (at least in theory). That being said, I try to plan in regular opportunities for students to 1)  "investigate" (do science) 2) "communicate" (share their questions, learnings, and interests and 3) "create" (which can include original art, creative expression, music and video productions).

 Teaching Challenge: How can I develop my students’ ability to apply unifying ideas to make connections across science content (among and between physics, chemistry, biology, earth and space science)?

In this vein, I want my students to communicate what they have learned about heredity (concepts rooted only to biology in this case) over the past week or so (as evidenced in these posted lessons).

Essential Questions #1 & 2- Writing Prompt- students have been digging deeply into the details of heredity and now they will complete an in-class writing prompt regarding two of the more globally-oriented and driving questions around which this unit has been planned.

For more details of the larger view of the unit please refer to the "Unit Map".

Prompt: students are asked to reflect on what each has learned about genetics, the nature of chromosomes, how they are inherited, and the various patterns of inheritance (including Punnett Squares and Pedigree charts). Using this information, she is to explain a thoughtful answer to each of the following questions. I will review the rubric (below the student prompt) for grading criteria and “look-fors”.

Essential Q #1: How are traits passed from one generation to another and why do members of the same family have different traits?”

Essential Q #2: Why are some traits hidden in one generation and expressed in the next?”

The rest of this time is devoted to an in-class writing period.

Closure: What did we learn? Where do we go from here?

5 minutes

Dirty Windshield Formative assessment

A number of corny references ("looking in the rear-view mirror" or "seeing clearly") are apropos to this assessment tool. However, it really is quite simple and resembles trying to see where we have gone and what students do and do not regard as clear just as in traveling by car on a road trip. The instructions are straightforward and students should easily complete it.

I would use the results of the class responses to determine what topics (and to what extent) any quick re-teaching and review is in order for the next day of instruction.

Lesson Extension & Follow-Up Activities

Essential Questions #1 & 2- Writing Prompt- Complete for class the next day…

For homework, I assign only the completion of the Essential Questions Prompt. Typically, students will need more time to thoughtfully communicate their understanding of genetics and to adjust their writing to the criteria.