Students will be able to identify the major concepts related to evolution and will visualize the process of natural selection.
It is important they know how adaptations and natural selection affect the survival of species on Earth. Students should understand the research and evidence behind the theory of evolution.
A computer and a projector will be needed for the Power Point lecture.
Text of Learning Exercise:
A. Charles Darwin
1. 1831-1836: Charles Darwin, a naturalist, travels around the world on the HMS Beagle.
2. He writes in note books his ideas about how animals evolve in an era when society did not agree with evolutionary views of life.
3. 1859: Darwins book, The origin of species gets published.
B. The Galapagos
1. Darwin studied the plants and animals on the mainland of S. America and compared them to those he found in the Galapagos Islands.
2. He noticed significant differences within the finches. Each type was a different species.
3. A species is a group of similar organisms that can mate with each other and produce fertile offspring.
C. Galapagos Finches
1. The birds had modified beaks as an adaptation for the specific foods available in their home island.
2. Adaptation is a trait that helps an organism survive and reproduce.
D. Natural Selection
1. By the 1840s Darwin theorized that natural selection was the mechanism of evolution.
2. Natural Selection is the process by which individuals that are better adapted to an environment are more likely to survive and reproduce than other members of the species.
3. Natural selection over long periods of time leads to evolution.
E. What affects Natural Selection?
1. Over production: producing much more species than can survive.
2. Competition: when offspring compete with each other for resources in order to survive.
3. Variation: any difference between individuals of the same species.
1. Helpful variations gradually accumulate in a species, while unfavorable ones disappear.
2. Variations are passed on:
a. Mutations in genes
b. Shuffling of alleles during meiosis
G. Geographic Isolation
1. A new species can form when a group of individuals remain separated from the rest of the species long enough to evolve different traits.
2. Geographic isolation can be caused by:
c. Mountain Range
3. The largest geographic isolation occurred during the split of Pangea millions of years ago.
(1) 1. Begin by posting slide one with a cartoon of a common concept about evolution.
(1) 2. Pass out the notes to the class (handout 1) and ask them to highlight key terms during
(1) 3. Put up slide two with the title of the lesson: have a student read the standards and
another student read the objective.
(1) 4. Put up slide three to introduce the lesson.
(1) 5. Put up slide four and explain what Darwin discovered in the Galapagos.
(2) 6. Put up slide five and explain the adaptation of the Galapagos finches using the diagram.
(2) 7. Put up slide six and explain natural selection. Ask the students how natural selection
applies to the moths on the diagram.
(1) 8. Put up slide seven to explain the three things that affect natural selection in a species.
(1) 9. Put up slide eight and describe variations
(2) 10. Put up slide nine and have the class give other examples of geographic isolation and why.
(1) 11. Explain to the class that we will be doing a lab that will represent natural selection and
adaptation in nature. Specify not to touch materials while passed out.
(2) 12. Pass out and explain Lab Contract (handout 2).
(1) 13. Collect the Lab Contract (handout 2).
(1) 14. Pass out materials: Plates, cups, pasta, pennies, Popsicle sticks, ohashi, forks ( Not
included). Pass out worksheet (handout 3).
(1) 15. Explain the rules to the lab activity: give the students a job to do.
(8) 16.Conduct the lab and organize.
(1) 17.Close by telling the students how the lab relates to the lecture. Next week they will learn
how genetics applies to evolution. Put up slide ten to consider.
(2) 18. Evaluate by showing a diagram (slide eleven and twelve) of a key terms which they
need to explain when asked to do so.
(30) Total time for lesson
Laptop (12 power point slides), 3 handouts (notes, lab contract, and worksheet), lab materials (chopsticks, popsicle sticks, forks, cup, plate, pasta, pennies), projector and screen.
STUDENTS WITH SPECIAL NEEDS:
The lesson is set up in order to accommodate all students.
Cambell, Neil A. and Reese, Jane B. (2002). Descent with Modification: A Darwinian
View of Life. In sixth edition, Biology (pp 428-442). New York: Pearson
Evolution. Prentice Hall Focus on Life Science. California Edition. (2001). Needham, MA:
Prentice Hall Inc.
Ann Hover, 7th grade Life Science Teacher: Rio Vista Middle School, Central Unified School District
10 question quiz on Mendel and Natural Selection relating to the activity.