Future Science Fair Project?

At some point I imagine my daughters will do some sort of science fair project in school.  Most elementary kids do at some point in their education.  An interesting question popped into my head the other day.  (Note:  This is probably 80% joking and 20% serious on my part.)  How long, on average, does a tube of chap stick survive before it is lost or destroyed in the washer?

Think about it.  Have you ever used an entire stick of chap stick before it is lost or destroyed?  I can honestly say I never have.  I'd be curious to see a study on the average survival time of chap stick.  This probably isn't a great science fair project, but it could be a neat little mini project at home with my daughters.  We could mark on a calendar the date on which a new tube is opened, and the date at which the tube is lost.  Are their differences between Mommy and Daddy?  Is more chap stick used during the summer or winter?  That's something an elementary student could answer through a simple research project.  And it would be a great way to introduce them to research methods.