SciGen Teacher Dashboard
Unit L3
Traits and Heredity
Reading: Mendel's Experiments
Duration: Approximately 180 minutes
This activity is entirely focused on an 8-page document that meticulously examines that work of Mendel and his pea plants. Some teachers will find this very helpful as a text for the study of alleles, genes, dominant, recessive, traits, and more. It is rigorous reading, but also is playfully written and illustrated. There are a number of activities that require writing and thinking. Teachers can assign this to groups, to individuals, or perhaps as homework to read at home with families.
LEARNING OBJECTIVES
Students will learn about the fertilization of flowering plants.
Students will learn how Mendel set up a controlled experiment.
Students will differentiate between the terms "purebred" and "hybrid."
Students will interpret data and diagrams related to multiple generations.
Students will apply knowledge of dominant and recessive traits to Mendel's work.
Teacher Tips
- This is long, complex document. Read carefully to decide how it will be most useful to you.
- While it is possible for the students to read the PDF of the script online, we suggest printing the script for the students so they can hold it in their hands and mark it as they read. Consider scaffolding the lesson for English language learners: you could let them preview the script before the lesson or read the dialogue silently once and ask questions to a partner.
- Page 8 of this study guide can be accompanied by or refer back to the comic strip of the family in L3.3 Lesson: Meet Mendel the Monk.
Teacher Tune-ups
Teaching Notes
STUDY PACKET OVERVIEW
- Page 1: Fertilization of the Common Pea Plant (30 minutes)
- Pages 2 & 3: Mendel Messes with Mother Nature (30 minutes)
- Page 4: Scientific Breakthrough! (30 minutes)
- Page 5 & 6: Combining Hybrids (45 minutes)
- Pages 7 & 8: Tracking Traits (45 minutes)
Page 1: Fertilization of the common pea plant (30 minutes)
The diagrams on this page explain the anatomy of a flower, the process of pollination by bees, and the development of a pea pod from the carpel.
Be sure to introduce the idea of self-pollination and cross-pollination. In self-pollination, a plant’s eggs are pollinated by that same plant’s pollen. In cross-pollination, pollen from one plant pollinates the eggs of another plant.
Communicating with diagrams
Diagrams are common in science texts. Ask students to explain how the diagram helps them understand the parts of a flower, as well as the processes of cross-pollination and self-pollination. Ask students what one change they would make to this diagram to make it easier to understand.
Pages 2 & 3: Mendel Messes with Mother Nature (30 minutes)
The first diagram on this page illustrates how Mendel controlled the pollination of his pea plants.
The second diagram shows the possible traits of the flowers, stems, and pods from these pea plants.
The chart on this page requires that students understand what “purebred” means.
Have students discuss the two questions at the bottom of the page and then write responses.
Using academic language
When students are asked to discuss the difference between two processes, they will be using the language of comparison and contrast, a frequently used academic language function. Students may benefit from a review of some of the words and phrases used when comparing and contrasting.
compare: just like, likewise, similarly, in the same way
contrast: however, whereas, unlike, on the other hand, conversely
For some students, a sentence frame may be useful.
In self-pollination, a bee may ____, whereas in cross-pollination, the bee ____.
Page 4: Scientific Breakthrough! (30 minutes)
The diagrams and explanations on this page show how when Mendel bred hybrid pea offspring, the traits of the parents did not blend. Rather, in the first generation of hybrids, certain traits disappeared entirely in favor of others. The flower did not become a lighter shade of purple. There was no medium-sized stem. Ask students why they think this happened.
Distinguishing everyday and scientific use
Ask students where they’ve heard the word "hybrid" before. What does it mean? They may talk about hybrid cars being powered by partly electric and partly gas sources. They may talk about hybrid dogs that have the characteristics of both dogs. However, these examples are not comparable to the case of the pea plant. This contrast may cause some confusion for students if they think a hybrid must always display a blend or mixture of visible characteristics from two different sources.
Page 5 & 6: Combining Hybrids (45 minutes)
This diagram shows two generations of pea plant hybrids. The first generation, F1, is exactly the same as the diagram from the last page. But F2, the next generation, shows that 25% the offspring from the second generation will have the trait of the white-flowering plant, the shorter stem, and the pinched pod. Students are asked to describe what happened.
After reading the paragraphs with the class, ask them to circle the correct word, dominant or recessive, in the box for each allele.
Answers:
Long stems – dominant
Short stems – recessive
Smooth pod – dominant
Bumpy pod – recessive
Pages 7 & 8: Tracking Traits (45 minutes)
The information on this page reinforces the concepts of dominant and recessive alleles in pea plants and the traits in F1 and F2 generations.
The two tables are for the students to complete. Have them discuss and sketch their responses.
Stem Length Answers:
long, long, long, short
Pod Shape Answers:
smooth, smooth, smooth, bumpy
This activity illustrates that these traits are all inherited independently.
You may want to refer students back to the comic strip of the family in L3.3 Lesson: Meet Mendel the Monk. The son had traits from both his mother and father for different features. (You can get your mom’s eyes and your dad’s nose!)
Students will draw pea plants based on the allele pairs.
Answers:
long, smooth
purple, long, smooth
BETA Version - Please send comments and corrections to info@serpinstitute.org
This project was supported by Science Sandbox, a Simons Foundation initiative dedicated to engaging everyone with the process of science.
Strategic Education Research Partnership
1100 Connecticut Ave NW Suite 1310 • Washington, DC 20036 • (202) 223-8555
info@serpinstitute.org