[infinite93]

I kind of agree about the letter grades confusing people..

I have always thought of it as class attendance... Imaging taking a 20 week course, then asking for the final at week 15 (75%).. sure, you might get lucky, but the odds are not in your favor... take the test at week 18 (90%) and you are only missing 10% of the material... Most professors will test more on the last material taught, so your chances are probably not 90%, but are still pretty good.

That's just way I think of it, and it correlates with the results we see pretty well.