What classification is
What did you actually do in the activity? You took a set of animals, found a characteristic they shared, and used it to separate them into groups.
Classification of organisms
Dividing living things into groups by the characteristics they share
This is what is meant by the classification of organisms.
Who chooses the criterion?
A classification is created not by the organisms but by the criterion we choose. Whether a lion and a cat end up in the same group depends on whether we picked "does it have fur?" or "does it live in a house?"
A classification is not right or wrong — it is useful or useless
Grouping by wings is not a miscalculation. But it hides the real relationships between living things. The whole chapter is built on that distinction.
On the next page we look at what a classification actually buys us.