Myth: Teachers are the MOST important factor in a student's growth and achievement.
The Truth: While teachers are important, years of research confirms that teachers are not the most important factor in student learning.
- About 60% of a student's achievement is explained by student and family characteristics; 20% pertains to school (with 10-15% being the teacher); 20% is unexplained (error). This has been confirmed in many studies.
- The correlation between poverty and test scores is nearly perfect.
- Funding gaps can account for half of the difference in test scores.
Myth: We can determine which teachers to fire or pay more by using standardized test scores.
The Truth: The overwhelming consensus among researchers is that test scores should not be used in high-stakes decisions like firing and compensation.
- There is a 35% chance a teacher will be misidentified as poor in any given year, and a 25% chance in two years. This is functionally the same as rolling dice.
- Research organizations against the heavy use of test scores in high-stakes decisions include the National Research Council of the National Academy of Sciences, ETS's Policy Information Center, the RAND Corporation, and the Economic Policy Institute (p.2).
Myth: Well, if we only base 50% of a teacher's rating on test scores, that will be fine.
The Truth: Using test scores for any significant portion of a teachers rating is biased and prone to enormous error.
- A rating based on test scores will inevitably take on unwarranted importance compared to other evaluation tools.
- Only 10-20% of teachers can be feasibly evaluated by test scores; the other 80-90% teach subjects and grades that aren't subject to test score analysis.
Myth: But using test scores to evaluate teachers is better than doing nothing!
The Truth: Using test scores to evaluate teachers will undoubtedly make our schools worse.
- Evaluations of teachers based on test scores assumes students are assigned randomly to classrooms. Parents, teachers, and principals will not be able to have a say in which students to assign to which teachers.
- Because of the high error rates, teachers will have strong cases to challenge terminations in court - even teachers who should be fired!
- Contract negotiations will be severely affected.
Myth: Three good teachers in three consecutive years can erase all the deficits of a child who is behind in school.
The Truth: The "three good teachers" myth is pure conjecture and has never been proved.
- The assertion is made mostly based on projection of single-year differences; it is not based on any actual policy outcomes.
- An analogy from Diane Ravitch:
This is akin to saying that baseball teams should consist only of players who hit over .300 and pitchers who win at least twenty games every season; after all, such players exist, so why should not such teams exist. The fact that no such team exists should give pause to those who believe that almost every teacher in almost every school in almost every district might be a superstar if only school leaders could fire at will.
Myth: Firing the "bottom" 5-10% of teachers would lead to big learning gains.
The Truth: This is, again, pure conjecture with little evidence to support it.
- There is no guarantee we could replace the "bottom" teachers with anyone better - especially when teacher salaries are in decline.
- Due to the high unreliability of identifying the "bottom" teachers, this policy would certainly dismiss good teachers and retain bad ones.
Myth: In New Jersey, only 17 teachers have been fired over the past 10 years.
The Truth: Without question, many more teachers have been removed for incompetence.
- This figure only includes tenured teachers dismissed in a formal tenure hearing.
- "Hundreds of teachers who receive the first tenure charges resign..."
- 40% of non-tenured teachers do not have their year-to-year contracts renewed, or voluntarily leave their schools; undoubtedly, many of these teachers realize they should not teach.
ADDING [9/2/11]: Bruce Baker has recently posted about the problems with Student Growth Percentiles, part of the recently announced NJ Teacher Evaluation Pilot Program.
For more information on teacher quality, we recommend:
Dr. Bruce Baker's School Finance 101 blog, especially his writings on Value-Added Teacher Evaluation.
The Economic Policy Institute
VAM: A Primer For Teachers
Next in our series: Merit Pay, Seniority & Tenure
Tuesday, 8/30/11: Standardized Testing
Wednesday, 8/31/11: Teacher Quality
Thursday, 9/1/11: Merit Pay, Seniority & Tenure
Friday, 9/2/11: Teachers Unions
Sunday, 9/4/11: Charter Schools & Vouchers
Tuesday, 9/6/11: Recap |
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