School district officials from throughout the nation will be in Minneapolis next week to recruit Minnesota college students for teaching jobs. Students attending the Minnesota Education Career Fair will find they are much in demand. U-S Secretary of Education Richard Riley recently warned of a nationwide shortage of teachers. Minnesota has traditionally had a surplus of teachers, but some teaching skills are in especially high demand. Minnesota Public Radio's Tim Pugmire reports... Saint Paul needs teachers...a lot of them. The district, which has a record number of vacancies this spring, has hired about 300 teachers each of the past four years to keep pace with rising enrollment and normal teacher