Beacon Unit Plan Library

Where We Come From

Suzan Smith
Fort McCoy School K-8 (Marion County Schools)


Can you roll your tongue? Do you have a widow's peak? In this unit students explore genetics and inheritance in an exciting way. Labs and hands-on, interactive activities include creating Marshmallow babies from an envelope of chromosomes, and decoding a riddle using the 4 components of DNA. Concepts covered in this unit are dominant and recessive traits, alleles, genotypes and phenotypes, heterozygous and homozygous alleles, Punnett squares, and DNA. Students enjoy this unit as they figure out where they came from!


What is the relationship between inheritance and your personal characteristics? In other words, where do we come from?

What are the variations in which traits can be inherited (homozygous/heterozygous; dominant/recessive)?

How are alleles formed and expressed physically (genotype/phenotype)?

How accurately do Punnett squares predict the characteristics inherited by offspring?


The planned duration of this activity is 10 days.

Associated Files

Unit Plan Overview     File Extension:  pdf

KWL Diagnostic/Summative Assessment     File Extension:  pdf

Genetics Vocabulary     File Extension:  pdf

Cooperative Workers Behavior Checklist     File Extension:  pdf

Summative Assesement     File Extension:  pdf

Lesson Plans

Wild Babies
During this first day of the unit, students consider the source of our traits and characteristics. This activity is designed to get the students thinking, intrigue their interests, and to involve them in class discussion. A KWL Chart will be initiated and used as the Diagnostic Assessment.

How Unique Are You?
In this second lesson of the unit, Where We Come From, the students use traits that they each possess to gain further understanding of dominant and recessive traits. In groups, they survey the class for various dominant and recessive physical trait characteristics. Groups create bar/circle graphs, compile class data into a table, calculate percentages, and recognize characteristics of dominant and recessive traits.

Marshmallow Babies
In this third lesson of the unit, Where We Come From, students pair up “chromosomes” and interpret the genotypes and phenotypes. Then, they use those genetic traits to create their own "Marshmallow Babies!" This is a modified version of an activity published by Patti Sorderberg in The Science Teacher, November 1992, pp 28-31.

Pair 'Em Up!
In the fourth lesson plan of the unit, Where We Come From, students learn how to use and verify the validity of Punnett squares by using a Weblink for instruction. They will also simulate a real-world situation by drawing “chromosomes” from a paper bag. Data will be tracked, students will calculate percentages, and cross check their predictions and results by using a Punnett square.

50:50 Chances
This is the fifth lesson in the unit, Where We Come From. Students reinforce the probability of gender by using a coin toss, as they continue to search for the answers to genetics questions by using mathematical expectations of probability.

Decoding DNA
This is the sixth and final lesson plan in the unit, Where We Come From and is an extension activity that reflects the standards for Marion County Schools in Florida for eighth grade. Students complete their KWL charts from the first lesson of the unit as a review for the summative. Then they decode a secret message using the four basic components of DNA, adenine, cytosine, guanine and thymine.

Web Links

This site summarizes the concept of the Reebop babies that was originally published by Patti Sorderberg. Pictures of adult “Reebops” are included on this site.
“Marshmallow Meiosis”

This Weblink provides basic review and instruction on using Punnett squares. Also included are examples that could be used with the students in class.
“Baby Steps Through Punnett Squares”

This Weblink provides additional practice problems regarding the cross between two organisms, including the dihybrid cross, trihybrid cross, and sex-linked traits.
“Genetics Practice Problems”

This Weblink summarizes the basis upon which I created the “Decoding DNA” activity. On pages 3 and 4 is information about telegrams written between Delbruck and Beadle using the parts of DNA as a coded language. Page 9 contains information about a toothpick model that Delbruck created for Beadle. The answer to his riddle is the same as the answer to my riddle in Decoding DNA.
The Delbruck Molecules

The National Human Genome Research Institute (NHGRI) created the Talking Glossary of Genetic Terms to help people without scientific backgrounds understand the terms and concepts used in genetic research. Simply click on the term of interest to open a page with a wealth of information, including the term's pronunciation, audio information, images and additional links to related terms. Students, teachers and parents will find the glossary an easy-to-use, always available learning source on genetics.
Talking Glossary

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