Based on the school visible in the background, this was at Creekside Elementary (which no longer exists), which would make it either fifth or sixth grade. I think it was fifth, which would make me about 10 at the time.
(I didn't even notice the damage to the photo until I'd scanned it in. Funny what one's eye skips over.)
I wish I had a photo of the fantastic Wurlitzer jukebox costume my dad & I made for me when I was 11. It looked kind of like this one only, y'know, made out of a cardboard box and with an 11-year-old inside. I carried a kazoo, and whenever anybody put a coin through the slot I would play them a song. :-D
[ETA: Upon further reflection, and considering my haircut, I think this must have been 3rd grade, actually, which would make me 8. I was trying to figure out why this didn't fit in with the two costumes I remember from the two years I was at Creekside...]