I used this technique when I taught elementary school and it worked wonders. I didn't make think of it myself, but first read of it in the 1980's in Lee Canter's Assertive Discipline
The idea is to reward desired behavior by putting marbles, one by one, into a jar. The sound of the marble plunking into the jar is a reminder that the behavior is being rewarded, and when the jar is full, a predetermined prize is given.
In our case, I had recently noticed that our "yes ma'ams" and "yes sirs" were slipping into obscurity, so I pulled out the trusty marbles.
I explained that each time I heard one of my children respond with "ma'am" or "sir" I would put a marble into the jar. When the jar was filled we would all go out for ice cream cones.
You would not believe the speed with which the "ma'ams" and "sirs" have returned to our house! There is something about hearing that marble hit and watching them slowly inch toward the top of the jar that lights a fire in children! Everyone does his or her part in getting those marbles to the top.
This technique can be used for any habit that needs reinforcing; Saying please or thank you, taking plates after dinner, making beds without being told.
For us, it is a handy visual and auditory reminder that reinforces positive habits. We will fill the jar and enjoy our ice cream cones a couple of times before I put the marbles away. By that time, the desired behavior will be a habit again.
Works for me!