On the News and Calendar page of the SPS website there was a headline - West Seattle High School to Move to a Six-Period Schedule Format - and this link to a letter from Carla Santorno.
In it, she outlines how WSHS is the only comprehensive high school with the 4-period format, how the review went, data used and that she has come to the decision that WSHS will go to a 6-period schedule for 2008-2009. Her reasoning is about academic achievement, availability of course offerings, system alignment within the district and mobility (interesting data: examining the high school classes between 2001-2007, excluding alternative schools, finds that about 10% of students will attend more than 1 high school. This might have some implications for the student assignment plan.).
She then writes about strategies in helping the switch work smoothly.
I wrote about this issue previously and once again, I am surprised that it has occurred (it was a parent generated complaint). Her reasoning seems pretty rational in terms of the benefits to students AND the direction the District wishes to go.