But the Answer was Right!

The cry of the Lucky Equation Grabber.

Not a relevant issue when the solution was wrong.

I grade the solution, not the answer.

This is a physics class, not a lucky guess class.

You can imagine the wailing and gnashing of teeth, but (as I wrote in the comments in a related thread over at Becky Hirta's) if you wanted to take the class from someone who doesn't care if you learn the physics, you went to the wrong place.

You need to be over at Wannabe Flagship where they give multiple choice tests and let kids use a crib sheet for F=ma and the other 100 equations you can derive from it, one for each possible problem on the exam.

They also don't notice that two algebra errors resulting in a correct answer equals two errors, not zero errors. I do.