Mendel's Smile

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SWBAT determine the resulting genotypes and phenotypes for certain traits based on Mendel's principles of dominant and recessive alleles.

Big Idea

With a flip of a coin students begin to understand Mendel's principles of genetics in order to create their own smiley-face offspring.

Video Introduction -Introducing Probability

1 minutes

This video clip introduces today's lesson where students are introduced to Gregor Mendel and the associated vocabulary terms that are necessary to facilitate student comprehension (and appreciation) of genetics.  This is a very basic lesson that will scaffold student understanding for future lessons that dive deeper into more complicated concepts of genetics.  The lesson does not fully master NGSS LS3-3: Apply concepts of statistics and probability to explain the variation and distribution of expressed traits in a population.  Rather this lesson works to build student vocabulary, interest, and confidence as the lessons progress into more complicated content that  will incorporate probability to explain the distribution of expressed traits in a population.  

Hook - A Happy Union: DNA and Genes

5 minutes

This lesson will start off with students making the connection between their prior knowledge of DNA and their new understanding of genes and the study of genetics.  Students need to respond to the following prompt:  How are DNA and genes related?  

The topic is purposely open-ended to encourage students to activate prior knowledge and be creative in their responses.  Students will have a few minutes to respond to the topic and are encouraged to flip through their Biology textbook for inspiration.  Many students will be inclined to compare and contrast the definitions of both terms, but the teacher should encourage the students dig deeper into their reflection of the prompt and identify specific examples or even draw diagrams.

Please view the Teacher Reflection regarding the implementation of the NGSS and activating prior knowledge with introduction of new curriculum.

Direction Instruction - Mendel's Contributions

25 minutes

As an introduction to the Genetics Unit, students will transcribe the Lecture Notes - An Introduction to Mendel which highlights Gregor Mendel's contributions to our understanding of heredity.  Students are encouraged to read each slide and determine which are the most important facts to record on their paper.  As a college prep course, it is crucial that students learn the skills to decipher important content versus supporting examples.  Students are reminded that most of the content that is provided through the lecture notes is also reviewed in the Biology textbook.  

Annotation Support: As a tool to guide students, the teacher is able to  annotate over the top of the power point slides to either highlight main ideas with the highlight feature of the Active Slate/Promethian software.  The teacher is also able to write or draw over the top of the slide (annotate) to bring the students' focus to a certain diagram or phrase.  The annotation of the lecture notes is a support to assist students in their attempt to identify the most important content on each slide.  Not every slide is annotated and not every set of lecture notes need annotation.  The students know that when the teacher annotates the slide that the content, diagram, or information being presented is important and needs to be recorded on their paper.  It is the goal of the course that students progressively become more independent in identifying the most important concepts and by the end of the course, the teacher only has to verbally highlight important features because students will have already been able to identify the most important content on the slides.

Guided Practice - Genetics With A Smile

20 minutes

Students will work with their neighbor to complete the Genetics With A Smile Activity.  Using the flip of a coin, each partner will determine their contributing parental allele for each of the listed traits.  Once each partner has determined their contributing allege for each trait, the partners will determine the genotype and the resulting phenotype of the offspring.  

Students will fill out the data table on the participant handout to track the progress of the activity.  Once the students have completed the data table they will create a sketch of the resulting offspring that has been creating through their "genetic" contributions of flipping the coins.  Students enjoy the creative opportunity to draw their offspring.  

Video Clip of Collaborative Groups

Genetics With A Smile - Student Work Samples: The students worked collaboratively to determine their own individual allele for each trait and then combined their results to get the genotype and phenotype of the offspring.  Each group's results (offspring) were different because the outcome of the activity was dependent on each student flipping their coin to determine if their allele for each trait would be dominant or recessive.  

Sample of Student Drawing: The student drawing depicts the phenotypic characteristics of the offspring created through this introductory genetics activity.  Students really enjoyed the opportunity to create the genotypes by flipping the coin, rather than being told what the genotypes would be based on information from a worksheet.  The active student participation increased student buy-in and created a sense of ownership for the student pairs as they worked to complete the genotype and phenotype of their smiley babies.

A Step Farther - A Baby Beauty Contest: If there is time, students can enter their offspring in the Genetics With A Smile Beauty Contest which will be judged by their peers and the prize is usually a few points extra credit for their amazing efforts!

Going Deeper With Follow-Up Lessons: Genetics with a Smile is a great introductory activity to allow students practice with the vocabulary terms associated with genetics.  The concepts in this activity will serve as a foundation for success in future genetics lessons regarding punnett squares and more complicated ideas such as codominance/incomplete dominance.


Close - Smiles of Satisfaction

5 minutes

As a final review, students will use their lecture notes and textbook as guidance to complete the practice worksheet that reinforces the basics of Mendelian genetics and the associated vocabulary terms:

genotype, phenotype, dominant, recessive, heterozygous, and homozygous

Sample of Student Work #1 Most students' work looked like this sample and provided the correct answer to these quick review questions.  This lesson was introductory and a review for some students based on their middle school education so most students were quick to master the usage of the vocabulary terms and the basic concepts of Mendelian genetics.

Sample of Student Work #2: This student seems to be struggling with identifying if a genotype is homozygous or heterozygous.  It is crucial to assist this student in their understanding of this concept, otherwise they will continue to be confused with the remainder of the genetics unit.  Quick closing activities are an effective strategy to determine understanding and gauge the preparedness of the students for the next lesson.