For each grade 0 classroom, return the classroom number and the count of students.
return classrooms ;return grades of  #1 ;return #1 where  #2 is  0 ;return classroom numbers of  #3 ;return students of  #3 ;return number of  #5 for each #3 ;return #5 ,   #6
['select', 'project', 'comparative', 'project', 'project', 'group', 'union']