The rise of zero tolerance in the schools might be behind it – the State Education Department doesn’t have a firm handle on what’s behind the 69 percent increase in expulsions of public school students in the last five years. The Education Department says 193 of the 900,000 public school students in Missouri were expelled in the last school year. The Department’s Stan Johnson says it takes serious behavior problems to lead to an expulsion. The youngest student expelled last year was in the second grade.