Choosing Good Categories and Naming Them Clearly

Think about where you have seen this before. Libraries and shops depend on clear categories. A muddy label sends an item to a shelf nobody will search. This is worth learning because clear categories let someone else check or repeat your work.

Watch for it today, and when you spot it, tell someone what you noticed and how you knew. Ask yourself where else the same idea might be hiding, then go and look.

Here comes a new math idea. A good category is clear enough that anyone could sort the same way you did. Red, blue, and green are clear categories. Pretty and ugly are not, because people disagree.

Every object should fit in exactly one group, with no leftovers and no arguments. If you find yourself unsure where something belongs, your categories probably need better names. Write the names down so nobody has to guess.

Try this test for your categories. Hand your pile to someone else with only your category names and see if they sort it the same way you did. If they do, your names were clear enough. Try it once with someone beside you, then try it alone.