I don't know if singing counts, but if it does then I know how to play five instruments: piano, drums, recorder (but doesn't everyone?), harmonica and of course I sing.
I started learning piano when I was 6, and it turned out to be much easier than I thought. I took up lessons, but quit when I was 12.
I learned how to play drums in my 7th grade music class. We were given the choice of learning guitar, drums, piano, or music theory (which is how to read music). I chose drums because it sets the beat and sort of the mood too. But now I want to learn guitar.
I learned the recorder every year from 3rd to 6th grade. Because my teacher was epic-fail at effectively teaching music, we spent half of the year learning how to read music. Then the other half of the year would be spent learning only one song (Hot Cross Buns) because the other kids were so obnoxious we wouldn't get anything done. To think that teacher is my chorus instructor now.
We spend most days in chorus just practicing music theory (It's like a college student being in preschool) unless my chorus instructor is in Panic Mode (which is the three weeks before a concert where the only way she can make everyone who's in chorus for the credits get to sing is by threatening them with detentions.) In fact, she was such a bad chorus instructor I had to find a vocal instructor.
I learned the harmonica when I had nothing better to do over the summer before 8th grade. It was unusually easy, and it was lots of fun to play the blues about the drama that's always in middle-schoolers' lives.
*Sorry about that long ramble about the music in my life.