My rather ragged music experience as a kid was with a guitar with a bit of piano added (it is very difficult to maintain lessons when you get moved every year or two, and then there was the issue as to why in my whole two months of piano lessons I went through two teachers!). I did come away some basic knowledge: my fingernails are always short, guitar strings do not like staying in tune... and guitars are a chord based instruments.
So whenever my kids ask to start learning to play a guitar I tell them they have to be far enough along in the Level 2 piano book to recognize chords.
By the way... for my kids: The school starts with real instruments in 4th grade, for those kids who are interested. This year all but two fourth graders were in choir, band or strings... in previous years less than a dozen participated. It depends on how the program is run, and who the teacher is.
There is a list of instruments that they can choose from like violin, cello, clarinet, flute, trumpet, percussion, saxophone and some other basic ones. Then there is a list of instruments that are possible with music teacher permission like a baritone, double-bass, bassoon, trombone, etc (usually these are kids who are taking private lessons). But NO guitars nor keyboard instruments.
BUT... and a big but --- some schools with extra parent funding (lots of fundraising) can get some extras. One of those was getting specialized instructional electronic keyboards into the music room to use with even the kindergarteners ... AND then providing recorders for 3rd graders.
AND... now an even bigger but: The music teacher they got in the past couple of years has started an elementary jazz combo (a couple of the kids were getting private guitar lessons), and started an introduction to guitars class (kids had to provide their own instruments).
The basic school music is the "Standard of Excellence" series, which have basic tunes that are usually recognizable. Kind of like these:
http://www.amazon.com/exec/obidos/tg/detail/-/0849759382/ ... then the music the elementary kids play at concerts are usually recognizable -- with an occasionally very simplified version of music from a popular movie. One year it was the Harry Potter theme, and last week it was the Star Wars theme.
Since being a parent of two school musicians I can tell you that there is constant fund-raising. But that is nothing new... I think I still have part of comb set my mother bought at the hairdresser's thirty years ago... the hairdresser's daughter was selling them to get her (and mine) highschool's marching band enough funds for an out of state trip. Fortunately I have the best neighbors -- last year my son sold his entire box of band fundraiser Almond Roca to just four neighbors... we decided to not press our luck with the middle school band CD's (we like our neighbors, and want them to still like us!).