Actually, having the final be worth 25% of the grade is higher than I've seen for high school courses. Frequently it's 10-15%. But the people in the article who are surprised by this must not have calculated weighted grades very much, as it is no surprise to me something worth 25% of the grade isn't going to move the grade a huge whole lot.

For their example of a student with a B (85%) who gets a D on the exam (65%) will get a B- (80%) as a final grade:

85 x 0.75 = 63.75

65 x 0.25 = 16.25

63.75 + 16.25 = 80

But conversely, if the same student with the B were to get 100% on the exam, he or she would still only get a B+ (88.75%).

(Frankly, most teachers I've dealt with don't understand the implications of weighting grades or even how to do it properly. I'd say that Sergio in the article is ahead of the game there.)

The question isn't really about how much the final exam is weighted. It's about what is going on in the class to produce students who are getting a B over the course of the marking period and then doing much more poorly on the final. You want whatever grading system you use to reflect demonstrated achievement, so the final grade in the class shouldn't be that different from the average of what the student got on the exams.

Case in point--When my son was in 10th grade, I noticed that if I averaged his math test scores, he had a C, but he was actually getting an A in the class. Here's why. First the homework was graded for "completion" meaning that if there was something written on the paper, it was entered at 100%. Then the tests were given over two days. The first day they took the test and the second day they corrected their mistakes. Sometimes they even took the tests home to correct the mistakes. Anyway, if a kid did the corrections correctly he could get half the points back (for example, if he originally got an 80, and he got all the corrections right, he would end up with a 90). Finally, the teacher would give out extra credit work that the students could complete at home, which tended to really bump up the grade.

I've heard of schemes where the homework piece only helps a student's grade, but I haven't personally seen a course where it is formally in place. So a kid who aces the exams but does no homework would get a grade that is based on test scores only.