Points vs weights

Something I've been noodling over the last few days is points vs weights for grades. I've always done weighted grades so how many points something was worth wasn't that important, the computer would calculate the weighted grade. But that can be confusing. I had a situation where a student was missing some assignments. She worked really hard to make some of them up and bring up her grade, but she left off one that was more heavily weighted than all the others. As a result, her grade didn't move much. Explaining that to her was difficult, to say the least. It was at that point I began to think about straight points.  If it was just straight points, the grading would be much, much clearer to the students.  And honestly, in all my graduate classes it's straight points and therefore so much easier to keep track of. So I've been playing around with that, but I'm running into a couple of roadblocks I'm having difficulty navigating.

The primary roadblock is how to set it up. If I want tests to be worth more they clearly need to have more points attached. That's easy. But, let's say tests are worth 100 points and homework is worth 5. If I want homework to be only 10% of the grades then theoretically I can't have more than 2 homework assignments if I only have 1 test. Does that make sense? If the unit is 3 or 4 weeks long, that's only 2 homework. Yes, I know, I don't grade all the homework, but essentially that means I can only include 2 grades for whatever I do assign. If a unit is a couple of weeks long, there will be 3 or 4 homework. Some units have homework every night. Which leaves me in the predicament of either making the test worth more so give it more weight or keeping the homework really low. So I'm thinking I have to set guidelines of some sort. Either individual things have to be worth a set amount of points; homework is 5, tests are 100, labs are 75, etc.; and then align the assignments to the unit to get the right percentages for each category. Or have a set number of points per unit and adjust the assignments accordingly. So if a unit is worth 200 points. A lab might be worth 50 points or 25% of the points. Homework would be worth a total of 20 points so if there were 2 homework, 10 points each or if there were 4 it would be 5 points each. Citizenship would be 20 points and that would be split between the weeks in the unit. Quizzes could be another 20 points and that would leave 80 points for the test. Clearly, the test and the lab are worth the most. That is kind of the way I'm leaning. So each unit would be slightly different depending on the assignments in that unit but I could post that beforehand and the kids would know exactly what they need to do to get the grade they want. This would also make including 20% for the final exam super easy because I would just make it worth 20% of the total points. Super easy.

Which leads to my next problem, how many points should each unit be? In AP Chemistry, which is where I started this, I have 12 units. My initial thought was 500 points per unit which amounts to 6,000 points over the year. Then I was thinking 200 points per unit which is 2400 points per year. That seems a little more reasonable, but the problem then arises if a student knows something is only worth a couple of points it becomes unimportant to them. So if homework is worth 5 points, they may not be so inclined to do it. And since each grade is an integral part of the overall grade, this could become a problem. So I was thinking of going for the higher points just because to the students it will seem more important.

So that's where I'm at. I'm leaning towards the 'each unit is worth the same points' and then adjusting the points of the individual assignments within a unit. I think this will be easier for me. Also, it will allow me to adjust things on the fly. For example, if one unit doesn't have a good lab I can shift the points around to more homework and more on the test. It gives me a little flexibility. Also, this will force me to plan out the unit beforehand so I know exactly what I'm doing. I think this is the way I will go.