Sitthixay Ditthavong, Associated Press
A large group of public school teachers marches past John Marshall Metropolitan High School on Wednesday, Sept. 12, 2012 in West Chicago.

Families in Chicago are sending their children back to school after a teacher strike that highlighted the difficulty of evaluating teacher quality. In order for parents to know they are entrusting their children to effective teachers, it is important that evaluations be able to accurately measure teacher quality.

Despite reaching agreements on many issues before the strike began on Sept. 10, teachers disagreed with the city of Chicago that student test scores should account for 40 percent of teacher evaluations. Teachers believed giving test scores such weight would deter good teachers from working in areas of high poverty where student test scores remain stubbornly low.

According to retired principal Leon Hundall, quoted in the Grio, the test score stubbornness is partly due to overcrowded classrooms and "deplorable" conditions in the poorest areas. Another factor is summer learning loss, which disproportionally affects low-income kids. Tests measure growth from one end of the year to the next and do not account for any backsliding over the summer months when teachers are not with their students.

Furthermore, tests align to grade-level expectations, rather than actual student growth. If an incoming fourth-grade student is reading at a first-grade level in September, but rises to a third-grade level by June, that student has made two years of progress, but will still test well below grade level on an end-of-year test.

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Public schools in Ann Arbor, Mich., are working to increase the accuracy of student testing through computer adaptive testing that allows students to demonstrate their actual academic level, regardless of their official grade level. By administering these tests at the beginning and end of each school year, teachers, districts and cities can more fairly measure actual student gains per year. This would give families better information about the quality of their students’ teachers.

For now, the city of Chicago compromised with teachers, deciding that students’ test scores will account for no more than 30 percent of the evaluation of teacher effectiveness. Other measures, including classroom observations and parent surveys will account for the other 70 percent.