In exchange, the Bill & Melinda Gates Foundation is handing them the biggest pile of cash it has spent on education programs in about a decade. The foundation announced $290 million in grants to the four groups yesterday, plus an additional $45 million for education research aimed at uncovering what exactly is an effective teacher.

The grants include $100 million to Hillsborough County Public Schools in Tampa, Fla., $90 million to Memphis City Schools, $60 million to a coalition of charter-school organizations in Los Angeles, and $40 million to Pittsburgh Public Schools.

Vicki Phillips, director of the foundation's K-12 education program, said the investment was big, the ideas bold, and she hoped the impact could rock every school and every district in the nation.

Foundation cochair Melinda Gates said she and her husband, Microsoft cofounder Bill Gates, considered education reform one of the toughest issues the foundation has taken on. The foundation is best known for its work fighting diseases like AIDS and malaria worldwide. "Any time you're trying to change a system and really have some innovative approaches, it's going to take some long-term work," Melinda Gates said.

The foundation picked four diverse organizations to work with: from the four corners of the United States, of a variety of sizes and ethnic mixes, all with problems and some successes meeting the educational needs of their students.

A fifth district was in line to join the others, but Omaha Public Schools in Nebraska dropped out at the last minute after it could not meet the matching requirement of the grant.

The projects have several central themes. They will focus on teacher training, put the best teachers in the most challenging classrooms, and give the best teachers new roles as mentors and coaches while keeping them in front of children. They also will get rid of ineffective teachers and use money to motivate people and schools to move toward these goals.