In another article ("Learn the Difference Between Affect and Effect") I commented that I almost never see the words affect and effect used correctly. In fact, misuse of these words is so common that I have come to believe that most people no longer have a clue about how they are properly used. Probably most people are not even aware that they are two separate words.
Another pair of words that I see misused far more often than not is than and then. As with affect and effect, than and then are so commonly misused that I suspect that more than mere carelessness is involved. I now believe that many people are either unaware that they are two separate words, or if they are aware of the two words, they have no idea of which is which.
Unlike then, than is not related to time. Than is used in comparative statements.
~Another pair of words that I see misused far more often than not is than and then.
~He is taller than I am.
~Other than the interest on a small inheritance, he had no income.
~Today's students certainly do seem to read less than students in previous generations did.
~We learned more on the playground than we did in the classroom.
~Despite their lack of flavor, the hothouse tomatoes cost far more than those from the farmers' market.
Then is used either as a time marker or with a sequence of events.
~I took all of the exams in the morning, and then I spent the rest of the day catching up on sleep.
~Back then we knew what was expected of us.
~I bought apples from this orchard last summer, but I seem to remember paying more for them then.
~Look over the study guide first, and then if you still have questions bring them up in class.