Natural Selection

Alexandra Romero

Gorton High School, Westchester

Summer Research Program for Science Teachers

August 2007

Adapted from Sciencelink

Subject: Living Environment (New York State Biology)

Grade Level: 9th and 10th Grades

Time: Three class periods - 42 minutes each

Unit: Evolution, Genetics

Objective: Students will be able to:

· State Darwin’s theory of evolution by natural selection.

· Formulate hypothesis and graph

· Explain the key concepts of natural selection

Prior Knowledge:

Students should be familiar with the terms gene, allele, species, population, gene frequency and heritability from genetics.

Introduction:

Natural Selection is an evolutionary process by which the most adaptable individuals in a particular environment survive. Living things that are well adapted to their environment survive and reproduce. Those that are not well adapted don’t survive and reproduce.

Materials:

Different sizes of jelly beans
Brown bags
Plastic cups
Pencil

Procedure:

Day One

Brainstorm with students key terms:

evolution, adapt, survival of fittest, reproduction, genes, traits, environment, selection, competition, predator, prey

Distribute index cards and instruct the students to write the definition of the term, draw an illustration or symbolic representation of the term and write a sentence using the term.

Have students post one of their index cards on the classroom word wall.

Day Two

Show the provided illustration on an overhead projector or smartboard.

Have students observe and describe what is happening in figures 1-3. Record their answers on the chalk board or smartboard.

Distribute worksheet 1 to the students and go over questions. See worksheet 1.

Have students that are done with the assignment log into http://www.sciencenetlinks.com/Esheet.cfm?DocID=80 to either watch the movie (subscription required) or play an interactive activity on natural selection. (Nowhere to Hide)

Students should answer the questions of Nowhere to Hide for homework. Student worksheet is found on www.sciencenetlinks.com/pdfs/nowhere_actsheet.pdf

Day Three Simulation of Natural Selection

In this activity students act as predators of jelly beans which represent any species to simulate evolution by natural selection. Students are told that smaller jelly beans are easy to catch and taste better while bigger jelly beans are faster but taste bitter.

Divide students into groups of four. One person from each group will get the materials.

Each student will create a lab report as they perform the activity.

Students will poke five holes to bottom of brown paper bags and place a cup of various jelly beans inside the bag.

Have students shake the bag and count the jelly beans that fall through the holes. These are considered dead prey. Population of jelly beans that remain inside the bag will be consider “survivors” and the first generation of parents.

Record first generation results on their lab report..

Have students get a new cup of jelly beans (this represents the offspring of survivors) and place inside brown bag. Shake again. This process is repeated four more times and students observe the population frequency.

Reading Strategy:

Have students read article about wooly mammoth on http://www.nature.ca/notebooks/english/woolly.htm

Have students complete the worksheet about wooly mammoth. Log onto http://www.sciencenetlinks.com/pdfs/mammoth2_actsheet.pdf

Illustration

New York State Science Standards:

Standard 1. Performance indicator 2.3, 3.1

Standard 4. Performance indicator 3.1a-3.1i, 4.1a, 6