Me: …and a downward acceleration of 10 (feet per second) per second.
Student: Do you mean 10 feet per square second?
Me: I do not. I have no intuitive or explanatory idea about what a “square second” is or what it would measure. So I choose not to use as a unit of measurement.
Student: My wall calendar measures time with squared days. So a square second is 1/86400-th of a single calendar square.
Me: Get out.