Classification: Using a Dichotomous Key and Naming Organisms

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Science · Biology
SP-BIO-013 · Free to print and use in your classroom · substituteplans.com
Page 2
Classification: Using a Dichotomous Key and
Naming Organisms
Science · Biology · Grades 9 · 45 minutes
Time needed
45 minutes (one class period)
Prep
Copy the 2-page worksheet (one per student). No lab materials needed.
Technology
None.
Student
independence
High. Individual work with a partner check.
Copies to make
One 2-page worksheet per student
Materials
Pencils, Worksheet
Goal for today: Students will use a dichotomous key to identify organisms and will use the genus and species in
scientific names to judge how closely related organisms are.
Before the bell
☐ Copy the worksheet, one per student (2 pages).
☐ Write on the board: Taxonomy ranks from largest to smallest: Domain, Kingdom, Phylum, Class, Order,
Family, Genus, Species.
☐ Keep the answer key on your desk. No science background is needed.
Say this to start
Today we practice sorting living things into groups, the way scientists do. You will use a step-by-step key to identify
animals and then use scientific names to see who is related to whom. The key tells you what to do at every step, so
just follow the directions one line at a time.
Run of show
Minutes
What you do
What students do
0–4
Take attendance. Hand out the worksheet and read the
directions aloud.
Look over the worksheet.
4–12
Tell students to read the passage silently. Read the first
two lines of the key aloud and model: “Animal B has fur, so
we stop at line 1a: it is a mammal.”
Follow the example.
12–25
Tell students to use the key to identify animals A–E
(questions 1–5).
Follow the key one line at a time and record
the group.
25–38
Tell students to answer questions 6–10 about scientific
names and domains.
Answer the questions using the table and
reading.
38–42
Read the answers aloud from the key. Students check their
own work.
Correct mistakes in a different color.
42–45
Collect the worksheets and place them in a stack for the
teacher.
Hand in the worksheet.

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Science · Biology
SP-BIO-013 · Free to print and use in your classroom · substituteplans.com
Page 3
If things go wrong
• If a student cannot follow the key: have them point to line 1a and ask, “Does the animal match this line? If
yes, read the result. If no, go to 1b.”
• If students ask about a real animal not on the sheet: tell them real keys use many more steps and this one is
simplified.
• If a student finishes early, use the early finisher list.
• If the room gets loud, move to silent work for five minutes.
Early finishers
• Make your own dichotomous key for four school supplies (pencil, eraser, ruler, notebook) with yes/no choices.
• Write a mnemonic for the eight taxonomy ranks.
Support and challenge
• Support: Let students trace the key with a finger and cross out each line that does not match.
• Challenge: Ask students to add a new step to the key that would separate a bird that cannot fly from other
birds.
Notes for the teacher (you fill this in)
Jot a few lines before you leave. A full Daily Sub Report is in the free Sub Survival Kit at SubstitutePlans.com.
How far the class got / what to pick up next:
Students who were especially helpful:
Anything the teacher should know: