The first official week of summer is also the first week of summer school for thousands of kids in the twin cities. In St. Paul, summer school is mandatory for some students who did poorly on state tests. Only a little more than half of all registerd students showed up for the first day of class yesterday. Cy Yusten is an assistant superintendant for the St. Paul Schools. He says the idea that school is back in session sometimes takes a few days to sink in.