How I did homework this year in PreCalc...

I stole this idea entirely from the teacher who taught APSI last summer.  I was intrigued by it, so I implemented it in my PreCalc classes this past year.  My kiddos are begging me to extend the concept to AP Calculus next year because they loved it so much (you'll see why...).  I'm undecided.  I thought I'd write about it and get your take...

The premise of this homework set-up is that kids get rewarded for doing homework instead of being punished for not doing homework.  This is how I ended up doing it, which is a slight modification from the way the APSI instructor did it.

1. Once a kid completes a homework assignment, I spot check it for completion and ask if she checked answers in the back of the book (assignments are due the day before quiz/test day).
2. If the homework assignment looks thorough, I give the kid a hole punch on an index card (I have a star-shaped hole punch, but you could use a stamp, stickers, etc.).
3. One a kid has ten hole punches, she gets a 100% on a quiz grade (I simply added extra quizzes, called them "Extra Credit Quiz 1," "Extra Credit Quiz 2," etc., and excused everyone from it until/unless she got 10 hole punches).
4. That's it.

Modifications:

• I will probably make these Extra Credit Quizzes worth only half a regular quiz grade next year (which should increase their overall percentage by 0.5-1 on average, instead of 1-2 percentage points on average).
• My APSI instructor only checked assignments on certain days (and hence only checked certain assignments), but I found it easier just to let all assignments count towards the extra credit.  If I didn't have time to do homework checks one day, it wasn't a big deal--I told the kids to just remind me the next day.

What I liked...maybe even loved:

• I hardly ever had to grade homework!
• I still had to have at least two grades in a week, so I would take smaller in-class assignments for a grade (typically as a review of that week's warm ups).
• Occasionally, I would give worksheets that I counted for "an actual grade" in the gradebook and not as a homework check.
• Kids were super, super honest.
• When I took homework for a grade, I saw kids half*** their homework ALL THE TIME.  You know what I mean.  Sometimes a kid would just miraculously go from Question 3 to Question 43...and hope I wouldn't notice.  Or, somehow they'd get the answer from the back of the book with no supporting work.  Yet, with this new method, kids would tell me almost daily, "I'm done with 8.3 but I still have two more questions on 8.4." Because there was no punishment for not finishing those two questions (and because they still had more time), they seemed to be much more up-front about how much work they had actually done.  This was good for me, sure, but I think it was also really good for the kids to voice what they still had left to finish.
• I'm not sure any more or any fewer kids did homework when it was presented in this manner.  You'd think a lot of kids would just stop doing homework, but I honestly don't think it was any more than normal. There are kids who will do the homework no matter what and kids who will not do homework no matter what.  I don't think this changed that.
• Kids felt less pressure.
• I try to give kids as much time as possible to work on assignments in class, where they can ask me and their peers questions.  Because of this, they all typically have at least a very good start on their homework.  Is it really the end of the world if they don't finish every single problem?  Especially if they're working hard in class...? I'm asking in sincerity.
• No one asked at the end of the year if there was any extra credit they could do to raise their grade.  Of course, I warned them at the beginning of the year that this was it. 

My hesitations:

• Maybe some kids are falling through the cracks?  I'm unsure.
• If I do implement this in Calculus, then something else has to change, because I'm currently not giving quizzes for a grade either.  Their entire grade cannot depend on tests!  One thing I do want to change is make their quiz corrections a grade (due the next day as opposed to at the end of the semester).  I've also thought about giving short MC assessments every Friday, which could certainly count as a grade.
• Calculus is a different beast.  Most kids need to wrestle with concepts, and that takes time.  While I prefer that my kids do most of their work in class, they do need to set aside some of their own home time to really understand what's going on.

So...what are your thoughts?  Is this worth extending to calculus?  Or at least trying it?

I'm fairly certain that I'm keeping this method in PreCalc next year, but what about for Calculus?  Help!