High school students at "below basic"

On the August post about trends in high school achievement, Anonymous wrote:

"Looking at only the % of kids that are advanced or proficient does not take into account whether or not kids are progressing from below basic to basic. Increasing percentages of advanced kids could still mean a growing achievement gap if the below basic kids aren't taken into account also."

This was an interesting question and so PURE graphed the trend in the portion of students at the below basic level for the classes of 2005 through 2010. Again the approach is longitudinal, showing the percentage of students in these classes at the below basic level in grade 8 and again in grade 11. Results are in the bottom two graphs at http://www.purereform.com/PSSA8to11.html and show a recent increase in students at the below basic level.