NCPA - National Center for Policy Analysis

Evaluating Teacher Effectiveness

June 8, 2011

"The Widget Effect," a widely read 2009 report from The New Teacher Project, surveyed the teacher evaluation systems in 14 large American school districts and concluded that status quo systems provide little information on how performance differs from teacher to teacher.  The statistic from that report: 98 percent of teachers were evaluated as "satisfactory."  Based on such findings, many have characterized classroom observation as a hopelessly flawed approach to assessing teacher effectiveness, say Thomas J. Kane, a professor of education and economics at the Harvard Graduate School of Education, and his coauthors.

An ongoing study of teacher classroom observation in the Cincinnati Public Schools asked the question of whether classroom observations -- when performed by trained professionals external to the school, using an extensive set of standards -- could identify teaching practices likely to raise achievement.

Findings include:

  • Evaluations based on well-executed classroom observations do identify effective teachers and teaching practices.
  • Teachers' scores on the classroom observation components of Cincinnati's evaluation system reliably predict the achievement gains made by their students in both math and reading.
  • These findings support the idea that teacher evaluation systems need not be based on test scores alone in order to provide useful information about which teachers are most effective in raising student achievement.

The results presented here constitute the strongest evidence to date on the relationship between teachers' observed classroom practices and the achievement gains made by their students.  The nature of the relationship between practices and achievement supports teacher evaluation and development systems that make use of multiple measures.  Even if one is solely interested in raising student achievement, effectiveness measures based on classroom practice provide critical information to teachers and administrators on what actions they can take to achieve this goal.

Source: Thomas J. Kane et al., "Evaluating Teacher Effectiveness," Education Next, Summer 2011.

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