We’ve had a problem for the longest time with beverage containers.  My dd doesn’t drink juice (yay for her!), so the only drink I’ve been able to send with her to school in her lunches is water.  Well, those pull-top lids were impossible for a pre-K/Kindy kid to open so we resorted to a twist top water bottle that we washed and reused.  The only problem was that it leaked.  And bad.  Every month or so the leaking would get so bad that we’d replace the bottle and start over.  It just never occurred to me to look for a permanent “Thermos”, as we used to call them in the good ol’ days, because I figured a) she’d lose it and b) she wouldn’t be able to open it on her own.  I’ve heard about the FUNtainers, but never paid attention to the threads on car-seat.org about them because I figured they were more like sippy cups for the younger crowd.  Then I went to the Thermos area at the ABC Kids Show and actually saw a FUNtainer and practically begged for 2 samples: one for my dd and one for my ds.