Tying teacher evaluation to student test scores?

You might be interested in the choices made by our national education "deciders" on tying teacher evaluation to student test scores. If this is a great idea, then, surely, it's something they've chosen for their own children?
As you probably know, President Obama's daughters go to Sidwell Friends. Their answer:

“We don't tie teacher pay to test scores because we don't believe them to be a reliable indicator of teacher effectiveness.”

(Sidwell Friends faculty member, April 1, 2011)

Secretary Duncan's children go to Arlington, Virginia public schools. Their answer:

“We do not tie teacher evaluations to scores in the Arlington public school system.” 

            (Arlington school district teacher, March 31, 2011)

So, President Obama and Secretary Duncan: when do we get this sort of school system for all our children?