splenda: American truancy laws require that you be educated up to a certain age — there is no requirement that you be in school.
In places where truancy laws are enforced (and usually such laws are only enforced against lowerw class minorities), home school students should bring a letter from their parents. In general, kids who are out when most kids are in school are left alone if they look and act respectably (and that includes frum kids on days our schools have off and the goyim have class), in part since police have better things to do, and in part since they don’t want to be sued for false arrest.