Variation Author: Sharon Janulaw

Overview: In this lesson students will look at populations of living things and identify variations in physical features.

Lesson Concepts:

• There is variation within a population.
• Scientists study living things.

Grade Span: K–2

Materials:

• Pictures of populations or individuals of various living things

Advance Preparation:

— Gather pictures of populations or individuals of the same species.

Time: One period

Grouping: Small groups

Teacher Background:

Natural selection acts upon variation in a population. This is the basis of evolution. While young children cannot grasp this concept, they can understand that there is variation within populations, i.e., not all individuals in a population are exactly like all others. If students know this by the end of second grade, they will be prepared to understand natural selection in later years.

Teacher Resources: The following websites show pictures of populations.
• www.alumni.caltech.edu/~kantner/zebras/
• www.whozoo.org/Intro98/natarale/natgiraffe2.htm
• www.thecatsite.com/general/colors.html
• groups.msn.com/SaveTheWolvesFoundation/wolvs.msnw?albumlist=2

Teaching Tips:

Remember the purpose of the lesson. Individuals vary within a species. Keep this in mind as you have wide-ranging discussions with students about the animals they find interesting.

Vocabulary: variation, population

Procedure:

1. Show the students a variety of pictures of wolves or cats and pictures of a number of herding animals in their herds. Ask them if the animals of one type look exactly alike. If students see zebras or giraffes as identical to their relatives, ask them to look more closely.
2. Help the class to see that the patterns on the faces of zebras or on the necks of giraffes vary from one individual to another.
3. Repeat this process with a number of different species of animals.
4. Go outside and select two trees or shrubs of the same species. Ask students how they are alike and how they are different. Leaf shape, color, and limb arrangement all vary between individuals.
5. Close the lesson with this question: “If an animal or plant is the same species does that mean it is exactly the same as all others of its type?” Students should be able to communicate, in their language, that individuals vary.

Extensions:

You might consider using variation of the appearance or dietary preferences of the humans in the classroom. All the same species, but a lot of variation. This is a potentially fruitful topic, but could provoke sensitivity in some situations.