U.S. President Barack Obama says he is bringing Congress an ambitious overhaul of the country's education system.

A task force eyeing ways to boost teacher effectiveness in the Los Angeles school district is recommending aggressive changes in the way teachers are evaluated, paid, hired and fired.

Imagine if a computer could identify the weakest-link teachers a " the ones who should be told it's time to get out of the classroom.

It's not quite so simple, but a new policy in Houston allows teachers to be fired based on data that some experts say isolates a teacher's effect on his or her students' test-score gains.

Reform advocates say school districts should improve teacher quality in part by using such "value added" data. Dozens of districts, including Houston's, have already incorporated the concept into "pay for performance" systems. Education leaders in New York City and the District of Columbia are moving toward linking it to tenure or dismissals. But none has gone ahead as boldly as the Texas district.

Each year, thousands of Palm Beach County high school students skip college entrance exams and hurt their chances for higher education.

The dispute began innocently enough as a disagreement between parents over the menu at a masquerade ball for home-schooled teenagers.