. >> reporter: julia keleher, the secretary of education here, is pushing for aggressive change. many school buildings were half- full or damaged, so she decided this summer to close more than 250 of them. keleher says the system needed so scarce dollars could have more impact. >> the idea was to have buildings at 85 to 90% capacity so that you could buy sets of books that would benefit more students, put computers in that more students could access and f assiull faculty and have two social workers. >> reporter: keleher believes this will improve quality, which in turn will improve learning. puerto rico's graduation rate and test scores are far below the u.s. average. >> this year, in the eighth grade there was not one student, not on who demonstrated proficiency. >> reporter: but changes to the educational systempore fiercely d by both teachers' unions here. >> this is by far, the worst semester we've had in the history of public education in our system. si reporter: mercedes martinez padilla is the pnt of the teacher's federation of puerto rico. >> teachers are very anxious. te