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Toothpick Chromosomes
Resource ID#: 19321
Primary Type: Lesson Plan
This document was generated on CPALMS - www.cpalms.org
Students will use toothpicks (representing chromosomes) with dots on them (representing genes)
to understand how traits are passed from parents to offspring. They will understand the
relationship between genes, chromosomes, and traits.
Subject(s): Science
Grade Level(s): 7
Intended Audience: Educators
Suggested Technology: Document Camera
Instructional Time: 50 Minute(s)
Resource supports reading in content area: Yes
Freely Available: Yes
Keywords: Genes, chromosomes, heredity, traits, genetics
Instructional Component Type(s): Lesson Plan
Resource Collection: iCPALMS
ATTACHMENTS
Genetic Cross Diagram.docx
First Generation Answerspea plants.docx
Toothpick Chromosomes Student Directionspea plants.docx
LESSON CONTENT
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Lesson Plan Template:
Learning Cycle (5E Model)
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Learning Objectives: What will students know and be able to do as a result of this
lesson?
Students will understand the following concepts:
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Every organism has a set of instructions that determines its characteristics.
There are genes located in specific locations on the chromosomes.
Each gene determines a particular trait.
Heredity is the passing of these instructions from one generation to another.
Prior Knowledge: What prior knowledge should students have for this lesson?
SC.4.L.16.1: Identify processes of sexual reproduction in flowering plants, including pollination,
fertilization (seed production), seed dispersal, and germination.
SC.6.L.14.2: Investigate and explain the components of the scientific theory of cells (cell theory): all
organisms are composed of cells (single-celled or multi-cellular), all cells come from pre-existing cells, and
cells are the basic unit of life.
SC.7.L.16.3: Compare and contrast the general processes of sexual reproduction requiring meiosis and
asexual reproduction requiring mitosis.
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Guiding Questions: What are the guiding questions for this lesson?
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How are traits passed from parents to the children?
If a child looks more like one parent than the other, does that mean that he/she inherited more
genes from that parent than the other?
What is a chromosome?
What is a gene?
How are genes and chromosomes related?
Engage: What object, event, or questions will the teacher use to trigger the students'
curiosity and engage them in the concepts?
Engage the student using the following questions:
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How many of you know someone who looks very much like one of their parents?
How many of you have been told, "You look just like your father/mother?"
How many of you can roll your tongue?
How many of you have attached earlobes? Unattached earlobes?
Hold up your thumbs-let's see who has a straight thumb and who has a curved thumb?
When you clasp your hands together interlacing your fingers, do you put your left thumb over
your right thumb or your right thumb over your left one?
How do you think characteristics are passed on from parents to the children? If you look more like
one parent than the other, do you think you inherited more from them than the other parent?
Have the students write down their ideas of how characteristics are passed from parents to children
in their notebooks.
If you have access to Uncovering Student Ideas in Science Volume 2, page 129 has a great probe
called "Baby Mice" that could be used to introduce this lesson as well.

Explore: What will the students do to explore the concepts and skills being developed
through the lesson?
Students will be investigating the connections between chromosomes, genes, and traits that are inherited in
a guided inquiry lesson.
Tell the students: You will be modeling how characteristics are passed from parents to offspring in this
activity. You will work independently; following the directions you will be given.
Pass out a bag of toothpicks for each pair of students, the Genetics Cross Diagram and the student
directions worksheet. Have the students follow the directions on the worksheet. The students will be
modeling how traits are passed from parents to offspring by using toothpicks which represent chromosomes
and the dots on the toothpicks represent genes. Walk around and observe students as they are working and
assist ones who are having difficulty.

Explain: What will the students and teacher do so students have opportunities to clarify
their ideas, reach a conclusion or generalization, and communicate what they know to
others?
After students complete the worksheet have a class discussion to clarify their ideas.
Go over these points with the students:
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What did the toothpicks represent? What did the dots on the toothpicks represent?
When you crossed the purple and the white flowers and got all purple offspring was it because the
offspring only inherited the purple genes? What was the reason?
Where are chromosomes found in a cell? What are chromosomes made of?
Tell students: In your notebooks, look back at what you wrote at the beginning of the lesson about how
traits are passed from parents to children. Now write down what you have learned about the relationships
between DNA, chromosomes, genes, and traits: Chromosomes are made of DNA. Sections of the
chromosome are called genes. The genes determine traits in organisms. Heredity is the passing of the traits
from one generation to another.
Have students copy a diagram in their notebook similar to the one below to show the relationship between
DNA, chromosomes, and genes: http://www.phoenix5.org/glossary/graphics/CellChromoDNAGene.gif.

Elaborate: What will the students do to apply their conceptual understanding and skills
to solve a problem, make a decision, perform a task, or make sense of new knowledge?
To determine if students have a solid understanding of the concepts, have them create a model to show how
they inherited a trait from their parents such as tongue rolling, attached earlobes, or another of the traits that
were discussed at the beginning of the lesson.
Or have them continue to work with the purple and white genes in pea plants and answer these questions:
1.
2.
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What would be the possible offspring if you crossed a flower with a purple gene and a white one
with a flower that had only white genes? Only purple genes?
Could two white flowers produce plants with purple flowers? Why or why not?
Summative Assessment
Students could draw a diagram or explain in words the relationship between genes, chromosomes and
DNA.

Formative Assessment
If you have access to Uncovering Student Ideas in Science Volume 2 Page Keeley (Author), Francis Eberle
(Author), Lynn Farrin (Author), page 129 has a great probe called Baby Mice that could be used to
introduce this lesson. The teacher can use information gathered during the probe to see how students are
progressing in their understanding during the lesson.
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Feedback to Students
Teacher monitors group progress giving feedback during the lesson.
ACCOMMODATIONS & RECOMMENDATIONS
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Accommodations:
If most students in the class would have a hard time following directions on the worksheet independently,
you could do this as a teacher directed inquiry instead. If you have a few students with special needs, pair
them up with students who can assist them reading and completing the worksheet.

Extensions:
Make new sets of toothpicks to represent other traits such as the ones Mendel used in his pea plant
experiments. Evaluate students' understanding of the concepts using the different traits.
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Suggested Technology: Document Camera
Special Materials Needed:
Use flat toothpicks and a fine-tipped purple marker to make a dot on the toothpicks. Use liquid white-out
for the white dots. Place the dots in the same general location on all the toothpicks to model how the genes
are in a certain location on the chromosome. Make 16 toothpicks of each color dot for every pair of
students. Store the toothpicks in a plastic bag.
Make copies of the student handout and the Genetics Cross Diagram, which are located in the Lesson
Handouts Section. For durability, laminate the Genetics Cross Diagram. You will need one handout and
one Genetics Cross Diagram for each pair of students.
Make copies of the first and second generation answers and place in separate envelopes which are labeled
"first generation answers" and "second generation answers" on a table near the student groups. For the
second generation answers you could also make a copy of a Genetics Cross Diagram and draw on it the
correct arrangement of the toothpicks.
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Further Recommendations:
Do this activity as an introduction to how traits are inherited before you discuss Mendel's experiments or
Punnett squares.
Additional Information/Instructions
By Author/Submitter
This lesson was adapted from an article in Science Scope, April 2003 called "Toothpick
Chromosomes". It has information about extending the lesson to teaching about blood types, sexlinked traits, and Punnett squares.
SOURCE AND ACCESS INFORMATION
Name of Author/Source: Anonymously Submitted
Is this Resource freely Available? Yes
License: CPALMS License - no distribution - non commercial
Related Standards
Name
SC.7.L.16.1:
Description
Understand and explain that every organism requires a set of
instructions that specifies its traits, that this hereditary
information (DNA) contains genes located in the chromosomes
of each cell, and that heredity is the passage of these
instructions from one generation to another.
Remarks/Examples:
Integrate HE.7.C.1.4. Describe how heredity can affect
personal health.