School › Classification › Ages 10–11
Keys, kingdoms and scientific names
How scientists classify living things into kingdoms and smaller groups, why every species has a two-part Latin name, and how to build and test your own identification key.
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Taxonomy is the science of classifying living things. Scientists have catalogued about 1.5 million species, so they need a clear system to keep track of them.[1][7]
The system is named after the scientist Carl Linnaeus (1707–1778). Big groups are split into smaller and smaller groups: kingdom, phylum, class, order, family, genus and species.[3][1]
Animals, plants and fungi are in different kingdoms. Fungi cannot photosynthesise; they release digestive enzymes and absorb their food. DNA shows that fungi are more closely related to animals than to plants.[5][4]
Animals can be split into vertebrates (with a backbone) and invertebrates (without). About 99% of animals are invertebrates.[6]
Every species has one two-part scientific name: the genus and then the species, for example Canis lupus for the wolf. The genus starts with a capital letter. A species can have several common names, but only one scientific name.[3][2]
To identify a living thing, scientists use a dichotomous key: a list of steps with two choices each, based on features you can observe.[7]
Try it: Build and test a key
You need
- 8–10 pictures of different whole organisms (for example a spider, a beetle, a butterfly, a snail, an earthworm, a frog, a sparrow, a goldfish, a daisy, a mushroom)
- Large sheet of paper
- Pencil and sticky notes
Safety
Use pictures only; no live animals or picked plants are needed.
What to do
- Lay out all the pictures. List features you can see: legs (how many?), wings, shell, fins, leaves…
- Write a first question that splits the whole set into two groups, for example 'Does it have legs?'
- For each group, write a new question that splits it again. Use only features you can see, not 'Is it nice?'
- Keep going until every organism is on its own. Draw your key as a branching tree.
- Swap keys with another group. Can they identify each organism correctly using only your questions?
- Fix any question that confused them.
What happens, and why?
A dichotomous key gives two choices at each step, based on observable traits, until only one organism is left. Testing it on someone else shows whether the questions are clear enough to give the right answer every time.[7]
Play: Vertebrate or invertebrate?
Does this animal have a backbone (vertebrate) or not (invertebrate)?
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Quiz
Other ages: Ages 6–7 · Ages 15–16