Facilitating Outstanding Classrooms Using Size reduction Act (FOCUS Act)

Facilitating Outstanding Classrooms Using Size reduction Act (FOCUS Act) - Amends the Elementary and Secondary Education Act of 1965 to require the Secretary of Education to award formula grants to states for allocation to their local educational agencies (LEAs) to: (1) reduce class size, particularly in the early elementary grades, by using highly qualified teachers; and (2) create a continuum of small classes from kindergarten through third grade for all their students.

Permits LEAs to use such funds to recruit highly qualified teachers, test new teachers, and provide professional development that enables teachers to teach effectively in their content areas.

Requires 80% of an LEA's allocation to be based on its proportion of the state's low-income students, with the remainder based on its proportion of the state's enrolled students.

Requires LEAs that receive allocations to provide written notice to the parent of each child who is taught for two or more consecutive weeks by a substitute teacher or a teacher who is not highly qualified.

Directs the Secretary to: (1) provide for an independent evaluation of this Act's effectiveness in reducing class size and improving teaching in small classrooms; and (2) develop and maintain, through the National Center for Education Statistics, a database that accurately calculates class size for every school, school district, and state.

Amends the Education Sciences Reform Act of 2002 to require the National Center for Education Research, in the Institute of Education Sciences, to develop and maintain a web-based National Clearinghouse on Class Size to inform the public regarding class size reduction research, resources, and best practices.