"Do Our Answers Have to Be Correct to Get Full Credit?"

[eigen]

Moderately common in my science discipline to have homework graded on completion/effort.

Sometimes it's an "Ill grade one randomly" thing, but mostly it's just "did you do it and make a reasonable effort".

A lot of the learning comes from trying things, and then seeing what you did right/wrong, and I find my students take to that more when they don't feel like they're getting penalized for the practice part of things. The idea is for them to take what they've (hopefully) gotten better at and show me that on exams.

I'm guessing in this case the weight of the assignments is pretty low relative to the exams, for that reason.

Low, but not tiny. I usually keep it at 15-20% of the final grade, about equivalent to one of my midterms. 

Enough to ensure that most of my students are consistently putting in the effort on a regular basis rather than cramming for exams.

I also give additional suggested homework that is not collected and worth zero points.