A free printable classification worksheet for Grade 11 biology.
This free dichotomous key worksheet teaches students to identify organisms the way biologists do. They use a 5-step key to name six common Ontario trees from drawn leaf specimens, then write their own key for four local animals.
It also covers the rest of classification: the eight taxonomic levels, binomial nomenclature, and the three domains and six kingdoms. The answer key gives every tree name with the exact path through the key, plus a sample student-built key and a marking guide.
| Part | Skill practised | Marks |
|---|---|---|
| A | The taxonomic hierarchy | 3 |
| B | Binomial nomenclature | 4 |
| C | Domains and kingdoms table | 6 |
| D | Use a dichotomous key: six Ontario trees | 6 |
| E | Build your own key for four animals | 4 |
| F | Why classify? | 2 |
| G | Spot the mistake | 2 |
It supports the Ontario Grade 11 biology curriculum expectations in the Diversity of Living Things unit. The tree specimens are drawn, so the sheet prints clearly in black and white.
"Dichotomous" means "divided in two". A key is a list of numbered couplets. Each couplet gives two opposite statements about one trait, and each statement either names the organism or sends you to another couplet. Here is the tree key used in Part D:
| Step | Statement | Result |
|---|---|---|
| 1a | Leaves are needles | go to 2 |
| 1b | Leaves are broad and flat | go to 3 |
| 2a | Needles grow in bundles of 5 | Eastern white pine |
| 2b | Needles are attached singly to the twig | White spruce |
| 3a | Leaf is compound (made of several leaflets) | White ash |
| 3b | Leaf is simple (one blade) | go to 4 |
| 4a | Leaf edge is toothed, with no lobes | Paper birch |
| 4b | Leaf has lobes | go to 5 |
| 5a | Lobes are pointed and spread from one point | Sugar maple |
| 5b | Lobes are rounded, along a central vein | White oak |
To key out the sugar maple: the leaf is broad (1b, go to 3), simple (3b, go to 4), lobed (4b, go to 5), and its lobes are pointed and spread from one point (5a). That gives the path 1b → 3b → 4b → 5a. Students record a path like this for every specimen on the dichotomous key worksheet, so you can see exactly where any wrong turn happened.
Organisms are grouped into eight levels: domain, kingdom, phylum, class, order, family, genus, species. A popular memory aid is "Dear King Philip Came Over For Good Soup". Two organisms that share a lower level, such as genus, share every level above it too.
Each species gets a two-part scientific name, a system known as binomial nomenclature. The genus is capitalized and the species is lowercase, as in Canis lupus, the grey wolf. Scientific names avoid the confusion of common names. Cougar, puma and mountain lion are all Puma concolor.
| Kingdom | Domain | Cell type | Nutrition | Example |
|---|---|---|---|---|
| Archaebacteria | Archaea | Prokaryotic | Autotroph or heterotroph | Methanogens |
| Eubacteria | Bacteria | Prokaryotic | Autotroph or heterotroph | E. coli |
| Protista | Eukarya | Eukaryotic | Autotroph or heterotroph | Amoeba |
| Fungi | Eukarya | Eukaryotic | Heterotroph (absorbs food) | Mushroom |
| Plantae | Eukarya | Eukaryotic | Autotroph (photosynthesis) | Sugar maple |
| Animalia | Eukarya | Eukaryotic | Heterotroph (ingests food) | Grey wolf |
Part C of the dichotomous key worksheet asks students to complete the cell type and nutrition columns from memory. For more practice, try the biological kingdoms quiz.
These questions match the dichotomous key worksheet PDF. The printable version has ruled space for every answer and a table for the tree identifications.
Questions 8–13: for each kingdom (Archaebacteria, Eubacteria, Protista, Fungi, Plantae, Animalia), give its cell type and how it gets its nutrition.
Questions 14–19: use the key above to identify each specimen and record the steps you followed.
Open each part of the dichotomous key worksheet answers to check your work. The printable key is at the end of the PDF.
Part G of the dichotomous key worksheet targets the first and last of these.
When you move on to microorganisms, the bacteria quiz makes a good follow-up, and the evolution quiz links classification to common ancestry.
Yes. The worksheet and its answer key are free to download and print as a PDF, with no account needed.
A dichotomous key is an identification tool made of numbered pairs of opposite statements. At each step you pick the statement that matches your organism and follow it to the next pair, until you reach a name.
Each couplet should describe one observable trait as a clear either/or (has fur / does not have fur). Avoid opinions such as large or small, and check that every organism ends up with its own name.
Write the genus with a capital letter and the species in lowercase, both in italics when typed or underlined when handwritten, for example Canis lupus.
It is written for Grade 11 biology (the Diversity of Living Things unit) and also works for Grades 9–10 science review.
Ready to start? Download the free dichotomous key worksheet PDF (use the Download button above), print it double-sided, and keep the answer key pages for marking.