Grades

This is not a response to a specific question per se, but a theme that often shows up in my conversations with parents, especially those with kids in high school: "Why is my child doing so poorly in that class? He/She gets perfect scores on all the homework..." Sound familiar? Let's look at a couple of explanations.

REASON #1: Calculation Method
These are fictitious scores that I am going to use to help illustrate my point.

Basically, there are two ways which scores can be tabulated.
One approach to calculating a grade is a straight percentage: total points earned divided by the total possible. In this particular case, that means 323/395 = 81.7%, which would usually qualify as a B or B-. This method is popular because it is straightforward and easy to compute if you have a written grade book.
As more schools adopt grading software, however, teachers are getting more creative with how they determine a student's final grade. These computer-based systems allow teachers to easily create weighted categories and with them, a lot of confusion. Using the grade sheet above and the following weights, we end up with a very different outcome:
- Homework: 10%
- Quizzes: 30%
- Tests: 60%
First we calculate the percentages of the individual categories then apply the weights:
- Homework: 93/95 = 97.9%; 97.9 x (0.1) = 9.8
- Quizzes: 78/100 = 78.0%; 78.0 x (0.3) = 23.4
- Tests: 152/200 = 76.0%; 76.0 x (0.6) = 45.6
Add up the category totals and you have: 9.8 + 23.4 + 45.6 = 78.8
So now, instead of getting a B or B-, this person ends up with a C or C+. Big difference if you're talking GPA. If this were an actual grading schema, an extra 5 points on a test will impact the final grade considerably more than an entire homework assignment.

REASON #2: Completion Credit
I can't speak for all teachers, but those that I have worked with all have a similar philosophy when it comes to homework: if it's done, you get full credit. This is true regardless if the student gets it all correct or all wrong. All that to say, homework is usually a poor indicator of how well a student is understanding the material. If you really want to know how they're doing, look at their quiz scores instead.