Download Manipulating Punnett Squares

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Status: Published
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Resource ID#: 76036
Manipulating Punnett Squares
Students will learn how to draw, complete, interpret, calculate the probabilities, and figure ratios for single trait crosses with complete dominance
interaction.
Subject(s): Science
Grade Level(s): 7
Intended Audience: Educators
Suggested Technology: Document Camera,
Overhead Projector
Instructional Time: 2 Hour(s) 15 Minute(s)
Resource supports reading in content area: Yes
Freely Available: Yes
Keywords: Punnett Squares, Manipulatives, Probability, Heredity
Resource Collection: FCR-STEMLearn Diversity and Ecology
LESSON CONTENT
Lesson Plan Template: General Lesson Plan
Learning Objectives: What should students know and be able to do as a result of this lesson?
Students will know:
Different forms of genes are called alleles.
Dominant alleles are represented by capital letters and recessive alleles by lower case letters.
Genotype represents allele pairs that control phenotype, which is the observable expression of a trait.
Punnett Squares determine probabilities of genotypes and phenotypes.
Punnett Squares can only show possible offspring combinations, not actual results.
Students will be able to do the following:
Identify dominant and recessive allele combinations.
Describe the difference between homozygous and heterozygous genotypes.
Identify examples of genotypes and phenotypes.
Draw a Punnett Square to determine possible genotypes and phenotypes for offspring.
Analyze a Punnett Square to determine the probability that each genotype will occur.
Explain benefits and limitations of scientific models.
Prior Knowledge: What prior knowledge should students have for this lesson?
Students should already know the following:
Genes are the basic unit of heredity.
The outcome of the process of meiosis is four genetically different gamete cells with only half the number of chromosomes in each cell.
Gregor Mendel's experiments with pea plants determined the patterns of heredity.
Day 1: Activate Prior Knowledge
Have a student pass out a class set of the Gregor Mendel article from Biography.com. Since this is only a review to activate prior knowledge, use the section of the
article titled "Experiments and Theories." Inform students that they are to read the article independently. Students then discuss the following questions with each other
and as a whole class.
page 1 of 5 1. For what is Gregor Mendel known?
He is known as the father of genetics.
2. What is a hereditary unit?
A gene that can be passed from parent to offspring.
3. How many genes determine a trait?
For some traits, only one gene determines phenotype: one allele from the mother and one allele from the father.
4. Who were Mendel's contemporaries?
Doppler (Doppler effect), Unger (Botanist)
5. What was Mendel trying to explain through his experiments?
Mendel was attempting to explain patterns of inheritance.
6. Why did Mendel choose pea plants for his study how traits were inherited?
Mendel used pea plants that had simple, obvious traits; for example, either yellow or green peas, or tall or short height, purple or white flowers, etc. Mendel tended
a garden, and peas were part of what he observed on a regular basis.
7. What did Mendel do during his experiment?
Students should offer that Mendel began using pure-breeding plants, one parent having purple flowers and the other parent having white flowers in the P
generation. Mendel discovered that the F1 generation produced nothing but 100% purple flowered plants. But, when Mendel bred the F2 generation using the plants
from the F1 generation, he discovered that about 75% were purple flowered and about 25% were white flowered. He did this with other traits from the pea plants
and came up with the same results in the F1 and F2 generations.
8. What were the two most important conclusions that Mendel made?
1. The Law of Segregation: There are dominant genes and recessive genes that are passed on to the offspring, but is done randomly, so there is no telling which
offspring will get which gene.
2. The Law of Independent Assortment: Genes are passed from parent to offspring with no regard to other genes being passed to the offspring.
Guiding Questions: What are the guiding questions for this lesson?
What are the factors that determine the expression of traits?
How can inheritance be modeled?
What are the benefits and limitations of inheritance models (Punnett Squares)?
Teaching Phase: How will the teacher present the concept or skill to students?
Day 1 con't.
Pair students according to their reading ability. One student should be of a higher reading level than the other, but not so far apart in reading level that the weaker
reader is intimidated. This encourages peer teaching during direct instruction and guided practice.
Select students to pass out the following items for the next activity, one per each student:
Punnett Square Student Notes
Punnett Square Manipulative Sheet
A copy of the article "Punnett Square" from Saylor.org.
Have students read the article. Use the questions below to discuss the article.
1. Did Mendel invent the Punnett Square?
No
2. Who did invent the Punnett Square?
Reginald Punnett
3. Why did Punnett use the square he invented?
He was able to figure out what Mendel was trying to express in his published papers about what her understood about the mechanism of genetics.
4. Why do you think using a Punnett Square would be useful?
You can visually see how gametes combine to make a trait from two genes, one from each parent.
You can calculate the estimated (or predicted) probability of the offsprings' traits.
Allow for a couple minutes for open discussion on its usefulness.
Pass out baggies containing the pea color alleles. Each student pair will need about 25 green pea markers and 25 yellow pea markers. There are 90 markers per
sheet.
Green peas - Print these markers on green cardstock.
Yellow peas - Print these markers on yellow cardstock.
Begin the What a Punnett Square Can Do for You PowerPoint presentation. Note that certain items on the slides are numbered; these correspond to items on the
Student Notes Sheet.
Read Slide 1 to the class, and then complete Slide 2.
Tell students to use their Punnett Square Student Notes Sheet to complete this scenario with the teacher. (The scenario is also on the Student Notes Sheet.)
Have students set up a minimum of three of the appropriate gametes along the top and left side on the Punnett Square Practice Sheet in each available space as is
suggested in the scenario.
Encourage students to use the information from the article to help them explore how to complete the Punnett Square.
Instruct students to use the manipulative alleles with the Punnett Square Practice Sheet to complete their Punnett Square.
While students explore using and completing the Punnett Square, formatively assess by circulating and listening to peers working together in figuring out how to use
the Punnett Square. Once students have finished, have a brief class discussion about what kinds of problems they ran into while working with the manipulatives and
Punnett Square. This is a type of formative assessment and will help you determine your pacing and thoroughness of explaining each slide.
What were students able to figure out on their own? Allow students to explain.
What were students not able to figure out on their own? Allow students to explain.
Explain slides 3 – 5 to the students and have them add the information to their Student Notes Sheet (questions 1 and 2).
Using the manipulatives and Practice Sheet, explain Slides 6 – 15 (questions 3­6).
page 2 of 5 As each slide is shown, remind students to move the manipulative alleles down or across the Punnett Square as shown on the slide. Kinetic learners learn much
faster this way.
Point out that each letter represents a gamete with a particular allele and is passed on from parent to offspring.
Stop at slide 15 and tell students to let you see what they did with their Punnett square manipulatives.
Praise those that did well and tell them to write what they see on question 7 of their Student Notes Sheet.
Have a quick conversation with those that made a mistake.
Common mistakes are moving the gametes in a diagonal line and moving two gametes to the same square from the same parent.
Continue through slides 16-27 of the PowerPoint, explaining along the way, and have students continue to use their Punnett Square Student Notes Sheet to complete
the scenario questions. This will complete the Student Notes Sheet.
Allow students to offer answers, explanations, or questions as you see fit.
Continue to remind students to complete their notes as they go through the PowerPoint with you.
Have students create an exit ticket (Slide 28). Students can tear a sheet of paper in half and give the other half to their shoulder partner. Students will write a
response to the following question:
How do you use a Punnett Square?
Guided Practice: What activities or exercises will the students complete with teacher guidance?
Day 2
Pass out the following items:
A Guided Practice Problem Set for each student.
A Punnett Square Manipulitive sheet for each student.
Baggies of about 25 rolling tongue allels and 25 non-rolling tongue allels for each pair of students. Print each allel on a different color of cardstock; there are 90
markers on each sheet.
Allow students to work in pairs to help each other to complete Guided Practice #1. Circulate around the room and formatively assess and discuss errors with students
to facilitate their understanding.
Encourage students to use the Punnett Square Manipulative Sheet and tongue genes first before writing on their Guided Punnett Square Practice Sheet.
Any time you run into a student not understanding something, make sure that they demonstrate to you that they can complete the Manipulative Punnett Square
correctly. Then, concentrate on the misunderstanding at hand.
When most students have completed as much as they can with help from you and fellow peers, instruct students to check their own work while you show and discuss
the corresponding slides (Slides 29 – 46) with them.
Pass out baggies of about 25 tall plant allels and 25 short plant allels for each pair of students. Print each allel on a different color of cardstock; there are 90 markers
on each sheet.
Allow students to work in pairs to complete Guided Practice #2. Circulate around the room and formatively assess and discuss errors with students to facilitate their
understanding.
When most students have completed as much as they can with help from you and fellow peers, instruct students to check their own work while you show and discuss
the matching slides (Slides 47 - 65).
Exit Ticket (Slide 66):
Have students give a written response to the following question:
What kinds of information can you find by using a Punnett Square?
Day 3
Pass out baggies of about 25 purple flower allels and 25 white flower allels for each pair of students. Print each allel on a different color of cardstock (lavender and
white are suggested); there are 90 markers on each sheet.
Allow students to work in pairs to help each other to complete Guided Practice #3. Circulate around the room to formatively assess and discuss errors with students to
facilitate their understanding.
When most students have completed as much as they can with help from you and their peers, instruct students to check their own work while you show and discuss
the corresponding slides (Slides 67 - 86).
Independent Practice: What activities or exercises will students complete to reinforce the concepts and skills developed in the
lesson?
To reinforce the vocabulary, and for further practice at seeing the concepts in different ways, setting up and using Punnett squares, and calculating probability, use the
following worksheets:
SpongeBob Squarepants Genetics
SpongeBob Squarepants Genetics 2
Either of the above worksheets can be used as a formative assessment or homework assignment.
Pass out a personal copy to each student and have them complete the worksheet(s) independently. Circulate the room to be available for students who may still be
having small problems. Collect at least one of the handouts as a formative assessment.
Closure: How will the teacher assist students in organizing the knowledge gained in the lesson?
Show slide 87 in the PowerPoint. Have students get out a sheet of paper and respond to both questions. Allow about ten minutes for students to respond.
If students appear stuck, allow students to use their Student Notes and Guided Practice Sheets to help them.
If time permits, students can offer their input to the advantages and disadvantages of using the Punnett Square Model prior to showing the last slide (Slide 88).
Summative Assessment
Punnett Square Test: SpongeBob Squarepants Genetics Quiz
page 3 of 5 Formative Assessment
At the end of the lesson, students will create an Exit Ticket:
Day 1: How do you use a Punnett Square?
Day 2: What kinds of information can you find while using a Punnett Square?
Day 3: Wrap Up
What are some advantages of using a Punnett Square mathematical model?
What are some disadvantages of using a Punnett Square mathematical model?
Punnett Square manipulatives will be checked during Direct Instruction, Guided Practice, and Independent Practice.
Progress on all activity sheets during Guided Practice and Independent Practice.
Feedback to Students
Exit Tickets will be returned with necessary comments.
Punnett square
Use feedback to encourage students to do Punnett Squares correctly.
Discuss with students who didn't complete the Punnett Square correctly and help them figure out why.
ACCOMMODATIONS & RECOMMENDATIONS
Accommodations:
Use shoulder partners during direct and guided instruction.
Use a close statement handout for taking notes while students view the PowerPoint.
Provide individualized instruction during guided and independent instruction.
Extensions:
If students find themselves with little to do, provide them with this personal research project. Each student can choose any specific genetic disease. Students read at
least three different resources. Once research is complete, students will compose the following:
Punnett Squares showing possible genotypes and phenotypes of particular crosses.
A written description of the genetic disease and how Punnett Squares can be used to prevent genetic diseases from continuing.
Suggested Technology: Document Camera, Overhead Projector
Further Recommendations:
You will need to pre-cut and pre-bag your class sets of manipulatives prior to the lesson.
It may seem to take up more time, but it is better to have the different scenario gene manipulatives be grouped into their separate baggies. Some students are
driven to sort the alleles in neat little stacks of matching alleles. I have discovered that this takes their attention away from the task at hand.
You can make as many different alleles and scenarios as you wish in addition to the seven main traits Mendel studied for further practice.
SOURCE AND ACCESS INFORMATION
Contributed by: Sandra Crusher
Name of Author/Source: Sandra Crusher
District/Organization of Contributor(s): Marion
Is this Resource freely Available? Yes
Access Privileges: Public
License: CPALMS License - no distribution - non commercial
Related Standards
Name
SC.7.L.16.2:
Description
Determine the probabilities for genotype and phenotype combinations using Punnett Squares and pedigrees.
Identify the benefits and limitations of the use of scientific models.
SC.7.N.3.2:
Remarks/Examples:
Florida Standards Connections: MAFS.K12.MP.4: Model with mathematics.
Related Access Points
Access Point Number
SC.7.N.3.In.2:
SC.7.N.3.Su.2:
SC.7.N.3.Pa.2:
SC.7.L.16.In.3:
SC.7.L.16.Pa.2:
SC.7.L.16.In.1:
SC.7.L.16.In.2:
Access Point Title
Identify a benefit of using a model to explain how things work.
Recognize a benefit of using a model to explain how things work.
Recognize a model of a common activity.
Explain that offspring receive half their genes from each parent in sexual reproduction.
Recognize that children are born from two parents.
Explain that some characteristics are passed from parent to child (inherited).
Recognize that it is possible to predict whether a person is likely to inherit a particular trait from parents.
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