I was getting extremely frustrated one day last Summer when I went to do dishes and realized there was about 15 cups on the counter. Each time one of my kids were thirsty they would grab a new cup. I would say "don't you have a cup out already?" and the response was always the same, "I don't know which cup is mine." This resulted in lots of dishes and multiple loads a day.
I fixed the problem. I went out and bought cheap plastic cups in different colors. I bought a few of each color and assigned each member of the house a specific color. This way they always know what cup is there's. They now use one cup a day and sometimes that same cup last a couple days.
And in case anyone forgets, I have posted a note on the outside of the cabinet.This post is linked to the Frugal Tuesday Tip. Stop over and see what other frugal ideas you can find.