1. Introduce the topic of invasive species.
Tell students that every animal and plant species has a native habitat, or environment where it naturally and normally lives and grows. Explain to students that humans sometimes relocate a species, either by accident or on purpose. Ask: What do you think might happen if a species is moved out of its native habitat and into a new environment? Then introduce the vocabulary term non-native species. Tell students that introducing a non-native species to a new ecosystem can have negative consequences—the species may become an invasive species, or a species that causes harm to the new environment.

2. Explore the reasons people relocate species.
Ask students to brainstorm a list of reasons people relocate species. Prompt students to include a variety of reasons, such as:

• accidentally moving them; for example, through transportation or trade, or by moving firewood from one location to another
• purposely introducing them to help control a native species that is considered a pest; for example, to control pests that destroy crops
• importing ornamental plants to buy or sell
• importing animals as pets

3. Discuss examples of invasive animal species in the United States.
Provide students with the following examples of invasive animal species in the United States:

• European Starling: This bird was part of an effort to introduce to the U.S. all of the birds mentioned in the works of Shakespeare.
• Burmese Pythons: These snakes are imported into the United States as pets. In the Florida Everglades, released or escaped pythons have established themselves in the wild.
• Snakehead Fish: This fish was released into the wild from fish markets and has established a population in the wild.
• Zebra Mussel: This mussel attaches itself to boats, and has spread because of boats moving between different bodies of water.

Have students go to the USDA website and click on your state to see the invasive species in your area.

4. Discuss examples of other invasive species in the United States.
Provide students with the following examples of invasive plant species in the United States:

• Kudzu: This plant is a climbing vine native to southern Japan and southeast China. Its growth is out of control in the Southeastern United States.
• Andean Pampas Grass: This grass is native to the northern Andes, but is now a common weed near the California coast.
• Yellow Starthistle: This plant was introduced into agricultural fields in California and is now found in almost all 48 continguous United States.

Have students use the National Invasive Species Information Center website to find examples of invasive species that are insects, such as the emerald ash borer, or microorganisms, such as the influenza virus.

5. Brainstorm questions about how invasive species cause harm to their new environments.

As a class, explore the following questions:

• Why should we have native species?
• When do we use non-native species?
• What are the ecological, economic, and social impacts of invasive species?

Tell students that in a different ecosystem, a non-native species may have no natural predators to keep their numbers in balance, so they may multiply and crowd out native species or wipe out crops. Ask students to brainstorm a list of questions they have about invasive species. Ask: What are you curious about? What would you like to know more about?