Lesson 4: How Habitats Change

Big Idea

All parts of an ecosystem are connected, and when one part is changed, it affects the rest of the system.

Essential Questions

• How do habitats change?
• What happens when habitats are altered?
• How can human and animal needs be met in a shared living space?

Standards Addressed

NGSS:

• Disciplinary Core Ideas: ESS2.E (3-5), ESS3.A (K-2), ESS3.C (3-5), LS1.C (K-2) (3-5), LS2.A (3-5) (6-8), LS2.C (3-5), LS4.B (3), LS4.C (3-5), LS4.D (3-5)
• Science and Engineering Practices: 1-8
• Crosscutting Concepts: 1, 2, 3, 4, 5, 7

CCSS:

ELA/Literacy:

• Reading: RI.3.1, RI.3.2, RI.3.3, RI.3.7, RI.4.7, RI.5.7, RI.5.9
• Writing: W.3.2, W.3.8, W.4.2, W.4.8, W.5.8
• Speaking and Listening: SL.3.4

Mathematics:

• Mathematical Practice: MP.2, MP.5

National Geography Standards:

1, 2, 4, 5, 8, 14

Background Information

Habitats rarely stay the same. In spring and summer, plants emerge and grow; as seasons grow colder, many plants die off, lose their leaves, and many go dormant until the next seasonal growing period. Over longer periods of time, some species disappear, and new species may take their place. Sometimes the actions of people can change habitats. Natural areas are often removed or paved over for building, gathering resources, or may be eroded by foot travel or by vehicles.

Biodiversity is the term that describes the many different species sharing one habitat and is directly related to the health of a habitat. Usually there is a correlation between a high degree of biodiversity in an area and a healthy environment. When biodiversity is threatened, there are often negative repercussions for the environment.

The activities in Lesson 4 build on the concepts about habitats from Lesson 3 and introduce the idea of carrying capacity—the balance between the availability of habitat components (food, water, shelter) and the number of animals a habitat can support—and the limiting factors that affect animal populations. Examples are disease, predator and prey relationships, weather, pollution, and habitat destruction.

Concepts to Discover

• Food, water, shelter, and space to grow are the essential components of habitat.
• Their availability determines the carrying capacity of a habitat.
• Ecosystems go through constant change.
• People and animals affect a habitat.
• Wildlife populations can vary from year to year depending on limiting factors. Some of these are the result of natural processes, and some are caused by humans and other animals.

Pre- and Post-Assessment

What do we already know? Students predict, draw, and/or journal:

1. What happens when people build their homes near wild habitats?
2. How can animals and humans live side-by-side?

Student responses to these pre-assessment questions will reveal common misconceptions and indicate the growth of concept development. At the end of the unit, check again for understanding to see what has been learned.

Vocabulary

• habitat: the place or type of place where a plant or animal naturally or normally lives or grows
• biodiversity: biological variety in an environment as indicated by numbers of different species of plants and animals
• species: a group of animals that are more like each other than any other group of animals
• carrying capacity: the balance between the availability of habitat components (food, water, shelter) and the number of animals a habitat can support
• limiting factor: something—disease, predator and prey relationships, weather, pollution, or habitat destruction—that can affect an animal population
• population: a group of one or more species of organisms living in a particular area or habitat

Investigation 1: Observing How a Habitat Changes over Time

Materials

• chart (Worksheet 1: How Habitats Change) or chalkboard
• writing materials
• an area indoors or outdoors, large enough for students to run

Focus Questions

• How does our study site change over the course of the year?
• Are these changes due to human or natural causes?
• How do these changes affect the plants and animals that live there?
• Can the needs of humans and wildlife be met in the shared space?

Procedure

1. Explain to students that we will be studying several small “Squares of Life” to see how/if each changes over the course of the seasons.
2. Find a long-term study site that can be revisited monthly during the school year. Ideally these sites will remain undisturbed for the duration of the investigation.
3. In two to four distinct school habitats, mark off a 10- to 15-foot (3- to 4.6-m) square with flagging tape. Assign each student one of the plots as a study site.
4. Have students draw the area on Worksheet 1, and write a description of their plot. They should include an inventory of all species noticed, as well as weather, time of day, and other conditions. (Students can also use their science notebooks).
5. Revisit the plot(s) monthly and draw/describe what it/they look like and the weather/climate conditions.
6. Compare the current description with past descriptions.
7. Questions for Discussion:

• What kinds of changes did you notice?
• What do you think caused these changes?
• Did you notice any evidence of animal activity? Based on your observations, what do you think they were doing?
• What other actions of human beings could influence the biodiversity of a habitat? In what ways would they affect it?
• What questions do you have?

Investigation 2: Oh Deer! Observing How People and Animals Can Affect a Habitat

(Source: Project Wild K-12 Curriculum and Activity Guide, © Council for Environment Education, Houston, TX, rev. 2001)

(Note: Select a common ungulate, i.e. impala, for Kenya, or any species relevant to your locale)

Duration: 30-45 minutes

Group Size: 16 and larger recommended

Setting: indoors or outdoors (need a large area for running)

Materials

• Worksheet 2: Oh Deer! Tally Sheet
• String or tape to mark off lines
• Chalkboard or chart

Procedure

1. Review the essential components of a habitat with the students: food, water, shelter, and space.
2. Have the students count off in fours. All the ones go to one area, all twos, threes, and fours go to another area. Mark two parallel lines on the ground 10 to 20 yards ( 9 to 18 m) apart. Have the ones line up behind one line; all the rest line up behind the other line, facing one another.
3. The ones become the “deer.” They need to find food, water, and shelter to survive. When a deer is looking for food, it should clamp its “hooves” over its stomach (cross arms over belly). When it is looking for water, it puts its “hooves” over its mouth. When it is looking for shelter, it holds its “hooves” together over its head. A deer can choose to look for any one of its needs during each round or segment of the activity (e.g. when it sees what is available during that round), but it cannot change what it is looking for until the next round—if it survives.
4. The twos, threes and fours are food, water, and shelter—the components of habitat. Each student is allowed to choose at the beginning of each round which component s/he will be during that round. They use the same placement of hands to show what they are.
5. The activity starts with all players lined up behind their respective lines (deer on one side, habitat components on the other) and with their backs facing the students along the other line.
6. Begin the first round by asking all of the students to make their signs—each deer deciding what it is looking for, each habitat component doing likewise. (Management hint: Colored tokens or pieces of paper representing food, water, and shelter can be stacked at both habitat and deer ends of the field. At the start of each round, players choose one of the symbols before turning around to face the other group).
7. When the students are ready, say “Oh, Deer!” Each deer and habitat component turns to face the opposite group, continuing to hold their signs clearly.
8. When a deer sees the habitat component it needs, it should run to it. Each deer must hold the sign of what it is looking for until getting to the habitat component student with the same sign. Each deer that reaches the necessary habitat component takes the “food,” “water,” or “shelter” back to the deer side of the line. “Capturing” a component means the deer successfully met its needs and has reproduced (the habitat component is now part of the herd). Any deer that fails to find food, water, or shelter dies and becomes a habitat component and is available in the next round as food, water, or shelter for the deer that are still alive.
9. Record the number of deer at the beginning of the activity and at the end of each round (Use Worksheet 2). Continue for about 15 rounds, then gather students to discuss the activity and share their experiences. A small herd of deer might begin by having more than enough of its habitat needs. However, as the deer population expanded over several rounds, there was not sufficient food, water, or shelter. The carrying capacity of the habitat was exceeded. At that point, deer starved, or died of thirst or lack of shelter, and they returned as part of the habitat. This happens in nature also.
10. Post the data recorded during the activity on a chalkboard or chart. The number of deer at the beginning of the activity and end of each round represent number of deer in a series of years. This will be a visual representation of the fluctuation in deer populations. Wildlife populations will peak, decline, and rebuild as long as there is good habitat and sufficient numbers of animals to reproduce successfully.
11. Questions for Discussion:

• What do animals need to survive?
• How do these components influence “carrying capacity”?
• What are some “limiting factors” that affect the survival of animals?
• Why is good habitat important for animals?
• Compare habitats that people and animals use with those that people and animals don’t use.
• What questions do you have?

Assessment and/or Discussion

When thinking about taking action around the schoolyard, such as designing a new parking lot, we need to consider how that action affects the biodiversity of our schoolyard before making decisions.

How do the following actions affect the biodiversity of the schoolyard’s habitats?

• laying down a parking lot
• building a new wing onto the school
• mowing the lawn
• cutting down trees
• putting salt on the sidewalks in winter

Extensions

1. Have students draw examples or make posters of limiting factors and their effects on the carrying capacity of various habitats.