- Education and Science
Qualities of a Good Teacher Shown to Provide Lifetime Benefits for Students
A new very large US study has supported what many people have known from their own experience and that of their children - Good Teachers Really Matter and they Make a Lifelong Difference! Many parents remember how a good teacher really inspired them and perhaps provided the catalyst for career choices. Similarly parents have seen how good teachers can lift their children's grades; poor teachers can destroy grades and motivation. The new research study of data from 2.5 million students in the US demonstrated that good teachers have long-term benefits to the student's lives including boost to college attendance rates, higher earnings as adults and lowering teenage-pregnancy rates. It seems obvious that the arrival of a good quality teacher can help student get higher test scores and that this will help them improve their attitude to education and their performance in later tests.
But it is surprising that these benefits can be shown to affect the lives of student in the long term. This study users teacher's value-added scores as a metric of teacher quality, which is controversial. The results of this study add to this debate.
The study used information from two large databases. The first was a dataset of classrooms and test scores and teacher allocations for grades 3-8 from a large urban school district in the U.S. These data include more than 2.5 million students and 18 million tests for English (reading) and math for the period from 1989-2009.
The second dataset was United States tax records data spanning 1996-2010. Data used was information on student outcomes such as college attendance, earnings, and teenage births. It also included parent information such as retirement savings, household income and mother's age at child's birth.
The research study was able to match nearly 90% of the observations in the dataset, allowing large group of individuals from elementary school to early adulthood to be tracked, as well as their teachers.
The teacher quality assessment was based on teacher's "value-added" scores (VA). This is defined as the average gain in test-scores for the students in their classes, adjusted for various differences in student characteristics and past scores. Various school districts from Los Angeles to Washington D.C. have started to use VA to evaluate teachers. VA has its advocates and opponents. People who support it argue that using VA can improve student outcomes Critics argue that the gain in test scores do not accurately reflect a teacher’s true quality as there are many things that affect outcomes. Proponents argue that a good teacher will consistently tend to improve the test scores of their students. On the other hand a poor teacher will tend to reduce the grades of their students. Opponents have argued that VA unfairly penalizes teachers who may be assigned lower quality and poorly motivated students.
The findings of the study generally supported the claim that the VA accurately reflected teacher quality. As shown in the figures below when a teacher with a high VA score joins a school, the test scores increased straight away in the grade taught by that teacher. When a teacher with a high VA teacher leaves a school, the test scores fell.
The test score changes only occurred in the subject taught by that teacher.
Also and the size and direction of the change in scores matched what was predicted based on the teacher’s VA.
The study was also used to predict how long the benefits of a good teacher are sustained. The figure below shows the effect of high-scoring VA teacher for four years prior to the assignment of the teacher to the class and for four years after.
These results supported the validity of VA as a measure of teacher performance.
The study classified teachers as excellent, average and poor in terms of VA. Then the datasets were analysed to look at the longterm fate of students of teachers classified into these three groups over the long term.
The study analyzed information on earnings, college matriculation rates, where they ended up living and the age they had children.
As shown in the figures below the study found that students assigned to high value-added teachers are more likely to:
- Go to college,
- Earn higher incomes. On average, having a better quality teacher increased a child's total lifetime income by $9,000.
- Live in better neighborhoods,
- Less likely to be teenage mothers.
The average benefit of one teacher on a single student is modest. On average a student who had a single excellent teacher between fourth and eighth grade for one year would gain $4,600 in lifetime income, and would be 0.5 % more likely to attend college compared to a student with a similar background with an average teacher. However it is likely that the benefits accumulate.
The finding that teacher differences applied in both directions, with excellent teachers providing a benefit and poor teachers providing a disadvantage was a key finding supporting the study outcomes. There were significant differences in long-term outcome for students who had average teachers and those with poor teachers; and for students with excellent teachers compared with those with average teachers.
Doubt has been raised about whether value-added scores are in fact a valid measure of teacher quality. For example, one teacher might regularly increase test scores because their students are from more well to do families, or because their students are hard workers. These factors can be hard for researchers to account for in these studies.
The researchers concluded that the study showed that excellent teachers create wonderful value for the school and their students and that test score impacts and 'value-added' scores appear to be helpful in identifying such teachers. The researchers suggest that school districts should make more use of value-added scores in teacher evaluations, and consider removing the lowest performers after evaluating other performance aspects.
However, the researches and many other people have warned that applying value-added scores into policy is fraught with problems. Using VA with the knowledge of teachers might encourage cheating, teaching focused on tests. Teachers may also lobby to have certain students in their classes and to drop other students.
This research study was done in circumstances where nobody really cared about their ranking - as it did not affect their pay or job security. But these things will change if VA is introduced as a performance measure. Despite this many education researchers and school administrators suggest that even if VA is imperfect, the scores should be used with other measures for evaluating teachers.
Do good teachers make a difference?
© 2012 Dr. John Anderson