Warning: If you are 100% against standardized testing or 100% in favor of standardized testing, you shouldn't read this blog post. I'm going to some things that you will agree with, but you will be so blinded in anger over the things I say that you disagree with that you will never see the agreement parts. Besides, you have already determined your thinking on this matter so there is no point for you to hear the opinions of others.
Alright, maybe that warning was a little harsh. I apologize. In truth, I'd like to believe that the people who are on the extreme sides of this issue are a very small minority. Most people have their views regarding standardized testing, and I would guess that most people fall somewhere in the middle of the issue. I'm one of those people.
In an ideal world, the students will come to school and do their best everyday to learn--and testing wouldn't be necessary. The reason it wouldn't be necessary (in this ideal world) is because teachers would constantly gain an understanding of each student's level of learning through formative assessment practices; and students would ask questions about the things they didn't understand and keep working on these things until they got it. The motivation would be the attainment of knowledge.
To be fair, some students and teachers and whole schools work hard to (at least) approach this ideal world of education; but for the rest of us, we are still somewhere on our journey toward this world. We are striving to emphasize learning over "getting-a-grade"; but we still need effective ways to measure learning--and testing is part of this process; and standardized testing is part of this process.
Some Pros of Standardized Testing
In my view the "standardized" part of standardized testing is a pro. Every student takes the same test regardless of the factors that influenced their learning (such as their teacher, the curriculum, the standards, the state they live in, etc.). Think about the SAT test: colleges know that every student is taking the same test, so SAT scores can be compared to each other regardless of where in the country the test was taken.
Some Cons of Standardized Testing
It may be a challenge to teach all of the content that is covered in a standardized test prior to the administration of the test. Standardized tests typically have specific testing windows or a specific testing date on which to give the test. Since different school districts start and end on different dates during the year and have different days off due to holidays and other reasons, it might be hard to structure a course outline that completely covers all of the material that will be assessed on a standardized test. This occurs (sometimes) for Advanced Placement tests. These AP tests usually have a particular May date for their administration and many school districts finish their school years in June.
Some might argue that a "con" to standardized testing is that it might assess something that we don't teach or don't want to teach in the course. I believe that there is general agreement of what needs to be taught in each grade and that this is less of an issue than some would have you believe.
To me the biggest down side to standardize testing is that it gives the message to students (and parents) that the goal of school is getting a good grade on a (standardized) test rather than having the goal of learning. Sometimes standardized test results are treated with great importance with newspaper articles and school-wide celebrations. And sometimes these results are given too much importance when making course selection decisions for the next couple of school years. As I said before, schools should emphasize learning and should de-emphasize "getting a grade". A standardized test score should be just one piece of data that is used in conjunction with many other data points to make big decisions about a student's ability.