This is what I think...
The STAAR assessment is meant to be a 'Value Added Model' or VAM, which means that the state and districts will base a teacher's salary on the performance of the students she or he teaches. I think it's wrong to assume that there is an average mix of children - an even distribution of innate ability, family emotional stability, drive, or even access to proper nutrition - in every classroom of every district, so there is no valid basis for this kind of pressure on students and teachers.