Growing up on a farm, I'm quite familiar with growth. We grew all kinds of things in rural central Ohio - corn, wheat, cows, chickens, you name it. And so it is interesting to me that we are now talking about growing student learning. A few observations that we learned on the farm may help us understand student growth better.
Farmers know that the seed matters. They select the right seed with the right fertilizer to get the best yield for their crop. Next, you need to know how to prepare the soil. Good farmers go out and pick up large rocks that might stunt the young plant's growth, tilling the soil until it is fine and ready for the implanted seed. Once the soil is ready, you have to know just the right time to plant the seed, when and how to cultivate it so that weeds are removed. All of this is a lot of work and takes a lot of knowledge and skill.
But of course, there is more. If all it took were the knowledge and skill of the farmer, we would have bumper crops each year. Sometimes, a blight or mildew get to the crop and keep the seeds from growing. Sometimes there's too much rain at an unfortunate time in the cycle, or not enough rain. Infestations of insects or a neighbor's herd of cows can wreak havoc on the growth that the farmer so carefully planned. Sun, temperature, rainfall - lots of variables outside the farmer's control also influence how that seed will grow.
As a Value Added Leader in Ohio and one trained by ODE as a trainer in the new Student Learning Objective process, I can speak to the issue of student growth measures with some authority. I understand the numbers better than most and have worked with dozens of schools to analyze their data. From my knowledge of math and my personal experience working with school data, let me tell you without equivocation: you can NOT use these numbers as part of a teacher's evaluation. Period.
Like the farmer, a good teacher has skills and knowledge about how to reach students and cause academic growth, but also like the farmer, there are many factors outside of a teacher's control that impact these numbers. Truancy and mobility issues definitely impact student growth. Alignment of the district's curriculum can affect the growth. Length of time on task is another important factor, and is generally outside of a teacher's control. Some districts provide 90 minutes of math a day - others have 45 minutes. Guess which one will be rated a more effective teacher? The size of your class can impact growth. Excellent teachers with 22 students in a class may be effective one year only to be told that they are ineffective the next when they have classes of 32 students.
Analyzing data with school personnel from dozens of Ohio schools has convinced me of this: only the educators working inside the system can really interpret the data and use it to make decisions. Legislators in Columbus positively, absolutely, under no circumstances can use this data to make a judgment on the effectiveness of a teacher. Period. Exclamation point. End of story.
I'm not going to rate a farmer on the success of one crop, and we should NOT evaluate a teacher on the results of one test.