When Chemists Attack

There’s some argument on the merits of partial credit – giving students some points for getting at least part of a complex answer correct.  Sometimes, partial credit is beneficial – but the existence of partial credit causes another problem:

Some students simply won’t commit to an answer, hoping to somehow pass on a wave of partial credit.  As an example, consider the question below.  It’s part of a lab write-up where the students measured the pH of a solution of sodium hydroxide using pH paper and other indicators.

Question: Was the solution acidic or basic? _________________
Student answer:  Acidic, with the presence of base

Of course, the correct answer is “basic” – which was very obvious if the student had even glanced at the directions for using the indicators.  But instead of doing that, this student just thought he’d wing it, get done with the lab write-up a whole minute faster, and try to get points for his answer anyway.

I imagine that students keep trying this strategy because it has worked somewhere before.  But not today.