Lessons · Teaching · classifying living things
Grouping by what a thing is, not by where it lives
Living things are grouped by shared characteristics, and the groups nest inside each other. Vertebrates split into fish, amphibians, reptiles, birds and mammals by features like body covering, how young are produced and whether body temperature is regulated internally.
Hone is a place to practise a career, one idea a day. This is one of its lessons, written out in full and free to read without an account.
In beta. This lesson was written for Hone and has not yet been checked by a state certification officer. Practice material, not professional advice. What that means.
What it is for
A whale is a mammal and a shark is a fish, and they live in the same water and look alike. That single pair kills the idea that classification follows habitat, and it is the example worth having ready, because a class will offer the whale.
How to think about it
Ask about the body, never about the address. Fur or feathers or scales? Live young or eggs? Milk? Lungs or gills? Habitat and shape are the two things that mislead, because unrelated animals in the same place come to look alike.
Worked example
Mammals: fur or hair, milk for the young, warm-blooded, breathe airA whale meets all four, in the sea.
Fish: scales, gills, eggs, cold-bloodedA shark meets all four, beside the whale.
Amphibians start in water with gills and move to land with lungsWhich is why a frog needs both a pond and a bank.
Birds have feathers, and feathers belong to no other groupThe single cleanest test in the whole classification.
Your turn
Name the feature that only birds have.
Only birds have
Solve one, graded on the server
The trap
Using 'can it fly' as the test for a bird. Penguins and ostriches do not fly, bats and many insects do, and flight has been invented separately several times.