We don't need a longer school year, we need schools that actually TEACH.
Not teaching to tests, not spewing data by rote, but schools that impart the foundations of learning, first.
How to learn, how to reason, how to think, how to analyze information gained from ANY source, and use it to make informed decisions. In short, we need schools that create knowledgeable, thoughtful, responsible citizens, capable of making informed decisions, and desirous of such.
I consider myself lucky to be as old as I am. I graduated High School in 1982. With honors, much to the surprise of my guidance counselor, who, despite my tested IQ and being place in honors and "gifted" classes, thought I was basically white trash... on the day of graduation he tracked me down, handed me a set of honor cords and said "Here. I don't know how how you managed it, but these are yours" .
Now, why I say "lucky"? While the overall quality of eduction wasn't all that great, there were still many great teachers, who, not having to worry about standardized tests, actually TAUGHT, and I was fortunate to have been in their classes.
Today, many of them wouldn't have jobs in the education field: My Freshman year Honors Social Studies teacher would, by today's standards, be deemed a "bad influence" at best, and subversive at worst: He tended to pepper his lectures based upon the official study materials with cynical observations as to their biases, and it was from him that I learned to "read between the lines", and look elsewhere for what wasn't mentioned in the official histories.
My Sophomore year Gifted English teacher started the school year by saying: "I've a list of books that I'm supposed to cover, here it is. However, since you're all supposedly gifted, I'll leave those to you to read." Then he handed out copies of James Joyce's "Dubliners" to each of us, which he'd bought with his own money, since it wasn't part of the official curriculum, and said "This is one of the greatest works of literature in the English language, and this is what we're going to study."
And study it we did. He was brilliant, imperviously knowledgeable in his field and cynical beyond belief... but, he did one thing that so few of my teachers did at that point: He made us think, and had no problem explaining in great detail why were were wrong. At one point, he was expostulating upon one of the themes in Dubliners, that of self-perception, and especially how such tends to be different from reality, and how many of the images in the stories show that. I don't remember which story it was that we were studying, but, something within me "clicked", as he was talking, and, as I glanced around, I saw another student with that same look. He looked at me, I looked at him, and nodded... there's a description where the protagonist is looking at a copper kettle... and I knew that he knew, too, and he raised his hand and asked "Wouldn't the reflection from the copper kettle be an example of that? It's convex, and so his reflection would be distorted..."... and the stunned look on our teacher's face, as he realized the import of that question, was priceless: He'd never seen that, nor, apparently, had anyone else so far as he knew. He said that he was going to write it up and submit it, but I don't know if it ever went that far.
Regardless, that one moment drove all of us to learn it, experience it, know it for what it was: Life, in fiction created, captured, and made real in words. It was, for me, the moment when I SAW, for the first time, beyond just the words, above them, between them, behind them, and learned that how truly powerful and wonderful words can be.
My Sophomore year Honors Biology teacher was HOT. She also told me that I was her only hope for a perfect score on the NYS Regents Biology exam... which drove me to study HARD. Sadly, I only got a 93%.
My Senior year Honors Physics teacher was as smart a human being as I've ever met, ever. He was in his 60's, then, had retired from industry after selling the company that he'd founded and run successfully for over 30 years.
One of Einstein's more famous quotes is: "If you can't explain it simply, you don't understand it well enough." He understood Physics that well, and better: His was the patience that comes from true wisdom, knowledge and experience. We were all of us smart and impatient and irreverent... and, at first, disrespectful. He won all of us over, in short order, and I learned more in a year from him than from any other teacher in High School. Not just about Physics, but about life, by his example, as he taught us, talked to us, helped us. He treated us with respect, and from him, by his example, I learned how, and why, to treat others the same. He was a remarkable man, in all regards, and as great a teacher as I've ever had.
So, I was lucky: I finished High School before what came later, and had some wonderful teachers who not only taught, but inspired. Now, we've generations of teachers who are themselves victims of a school system that does not teach people how to think, how to reason, and so they cannot impart that to their students, cannot inspire them to surpass them, using what they taught as a foundation.
I call these times the "Age of Google": Knowledge everywhere to be found, for free, but each succeeding generation has less ability to use it to their advantage, to assess it, to determine for themselves what use can and should be made of it.
We have created an ocean of knowledge, and I fear not only that so many cannot swim, but that even fewer will sail upon it.
 Oh, and how I'd earned the Honor Cords? That was easy: I made the grades to do so. He'd written me off, years before, and so his surprise was simply due to ignorance. He was a small, petty human being, and his discomfiture on that day remains one of my most pleasant memories of High School.