Unit 5 – Weed Warriors
Activity 2 – What Makes a Plant Invasive?
Download Teacher Pages PDFActivity (Teacher Verison) PDF Download
Download Student Pages PDFActivity PDF Download
Materials & Setup
• Have students bring to class examples of plants they think of as weeds. Challenge students to look for plants that seem particularly invasive (capable of rapidly taking over large areas and inhibiting the growth of other plants).
Class Period One
For each student
• Student Page “Invasive Plants in Hawaiʻi” (pp. 22-30)
• Student Page “Invasive Plants in Hawaiʻi: Questions on the Reading” (pp. 31-34)
Class Period Two
• “Correct Responses for Invasive Plant Identification Quiz” acetate (master, p. 21)
• Overhead projector and screen
For each student
• Student Page “Invasive Plant Identification Quiz” (pp. 35-36)
Class Period One:
1) Have students display their plants in front of the class. As the class observes the plants, ask whether there seem to be any similarities among them. (If they need ideas, prompt students to look at characteristics such as leaf size, flower size and structure, the form in which plants grow, root shape and size, and so forth.)
2) Divide the class into groups of four to five students. Tell students that there are eleven characteristics that make some plants highly successful invaders. Have student teams work together to identify as many of these as they can, using the plants on display for ideas. Each group should make a list of the characteristics it identifies and explain their reasoning for each one.
3) Now tell students that there are seven main “dispersal mechanisms” that spread invasive plants into the Haleakalā rain forest. A dispersal mechanism is a means by which plant seeds are spread around, which enables the plant to become established in a new area. Challenge student teams to think of as many of the seven dispersal mechanisms as they can, write down their ideas, and explain their reasoning.
4) Give each student a copy of the Student Page “Invasive Plants in Hawaiʻi.” Have students read pages 22-25, stopping before the subsection entitled “Six Invaders of Concern.” When students have finished reading, have groups go back to their lists and use the information in the reading to determine the characteristics and dispersal mechanisms they missed. Groups should note these on their lists and place check marks by the ones they identified correctly.
5) As a class, discuss the similarities and differences between student lists and the ones given in the reading.
6) As homework, assign the rest of the Student Page “Invasive Plants in Hawaiʻi” as well as “Invasive Plants in Hawaiʻi: Questions on the Reading.”
Class Period Two:
1) Hand out the Student Page “Invasive Plant Identification Quiz,” and have students complete it.
2) Go over correct answers, using the acetate of correct responses. Discuss student questions.
3) Optional: Discuss the homework assignment with the class, using the questions on the Student Page “Invasive Plants in Hawaiʻi: Questions on the Reading” as a guide.
• How would you define a “weed”? Does invasiveness potential have anything to do with your definition? How about whether the plant is native?
• When talking about nonnative plants in Hawaiʻi, people often distinguish between “Polynesian introductions” brought here by early Polynesian settlers, and nonnative plants that were introduced later, after European contact. Does this division make sense to you? Why or why not?
• Participation in group work and class discussion
• Student Page “Invasive Plants in Hawaiʻi: Questions on the Reading” (teacher version, pp. 17-20)
• Student Page “Invasive Plant Identification Quiz” (teacher version, p. 21)
• Journal entries
How has this activity worked for you?