Kids are doing it all the time... graffiti-ing up sidewalks with no clue that they're in falling in line with global artists and creating something beautiful - they're just doing it legally ;) Anyhow, today I showed the kids a few Banksy pieces, and followed that with a chalk making project. Really, this was just as cool for me too.
So their homework? Take some stencils, and art-up their neighborhoods (or downtowns... or local parks... you get the idea.) I got the chalk recipe here. If anyone comes looking for some 5-year-old street artists, don't tell them it was us ;)