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.