Dichotomous Keys
Subject: Biology
Grade Level: 10th grade
Objective: Analyze how organisms are classified into a hierarchy of groups and
subgroups based on similarities and differences.
Goals: At the end of the lesson students will be able to:
1. Determine: Why Classify?
2. Practice classification skills in association with observation skills.
3. Define related vocabulary
4. Practice use of the dichotomous key
5. Exercise answering multiple choice questions for the state test.
Lesson Overview: This lesson will focus on the following concept, Why classify? The
teacher will use group work, class demonstrations, and partner work to translate the
material to the students. At the end of the lesson, the students will be able to apply their
prior knowledge; therefore, lay the foundation for expanding their knowledge in science.
Concepts to be taught:
1. Why Classify?
2. Taxonomy
3. Binomal Nomenclature
4. Genus
5. Taxon
6. Family
7. Order
8. Class
9. Phylum
10. Kingdom
11. Dichotomous key
Materials:
Textbook, notebook, board with markers, Overhead, “Engage” Example, Dichotomous
key handouts (Lab Manual A), EOC questions
Classroom Management Materials:
Bell, Stopwatch, Clothes pins Clock appointments **
Advance Preparation:
Gathering and copying notes and handouts.
Instructional Procedures:
Warm-up: In a paragraph discuss, “Why do scientists avoid using common names when
discussing organisms?”
Engage: The teacher will introduce the dichotomous key, and how the key works by
using a short example on the overhead. This will hold their attention just enough to begin
the lesson.
Explore: Students will look at a very unorganized store and discuss why it would be hard
to find anything. Students will discuss how they know where to find things at the grocery
store or walmart. Stores classify their objects and them put them in similar groups for
easy shopping.
Explain: The teacher will conduct a demonstration on classification by constructing a
dichotomous key using the demonstration data from the day before, and the students will
document on the same page of the concept map for students to have a copy in their notes.
Elaborate: (**) The students will demonstrate the same activity from the “Explain” step
by using a handout found in Laboratory Manual A provided by the teacher, constructing a
dichotomous key. As the students carryout the teacher will constantly check their work
by using the data in the constructed key.
Evaluate: The students will complete EOC questions, review the day’s lesson. They will
see the questions again on Friday’s quiz
Closure: The teacher will take the last few minutes: reminding students about the quiz on
Friday and working as a class to clean-up
Homework: If students do not finish the worksheet then they must finish it for
homework.
Consequence Homework:
Page 465
#1: Reviewing content 1-10 (write questions and answers)
#2: Understanding concepts 11-25 (write questions and answers)
Alternate Work for Inclusion Student: All students are on the same learning level, so
no alternative work is needed.
Materials Used for Instruction:
Textbook: Miller, Levine: Prentice Hall Biology. 2002
References: BSCS Biology, An Ecological Approach. 9th Edition. 2002
Rexba, Richard J.: Learning and Assessing: Science Process Skills. 4th
Edition
Duncan, Jerald: Student Review Guide: Biology I
Internet or electronic sources: No internet sources were used for this lesson.
NSTA Standards:
5 General Skills of Teaching a- Vary their teaching actions, strategies, and methods to
promote the development of multiple students skills and levels of understanding.
c- Successfully organize and engage students in collaborative learning using different
students group learning strategies. e- Understand and build effectively upon the prior
beliefs, knowledge, experiences, and interest of students