Dichotomous Keys Lesson Plan for 8th Grade Students

Topic: Dichotomous keys

Objectives & Outcomes

• Students will be able to build and read a dichotomous key, which is a tool for identifying different species of organisms.

Materials

• A blank dichotomous key template (provided in the worksheet section of this lesson)
• A collection of specimens that represent the different species you want to identify (e.g. plants, insects, etc.)
• pencils
• eraser

Warm-up

• Ask students if they have ever done a science project that involved identifying plants or animals.
• Ask them to explain how they identified the different species.
• Introduce the concept of a dichotomous key and explain that it is a tool for identifying different species.

Direct Instruction

• Show students a dichotomous key and explain how it works.
• Start at the top left of the key and identify the first feature. For example, if the first feature is "has leaves," then the key will lead to either "yes" or "no."
• Follow the key down to the next feature, which will again lead to either "yes" or "no."
• Continue down the key to identify the species.
• Explain the importance of using a dichotomous key to accurately identify species.

Guided Practice

• Have students work in pairs to build a dichotomous key for a particular plant.
• Provide guidance as needed to ensure that students are identifying the correct species.
• Allow time for students to present their keys to the class and discuss their findings.

Independent Practice

• Have students choose a plant species to research.
• Students should use their dichotomous key to identify the species and record their findings in a lab notebook.
• Encourage students to be skeptical and double-check their work.

Closure

• Have students share their dichotomous key and their observations with the class.
• Ask students to reflect on the process of building and using a dichotomous key.
• Ask students to share any challenges they faced and how they were able to overcome them.

Assessment

• Observe students during their independent practice, and provide feedback on their dichotomous keys and their observations.
• Have students turn in their completed dichotomous keys and a written reflection on their experience building and using a dichotomous key.