>My feelings now are that there really shouldn't be any mandatory homework.

Been there, tried it. Didn't work. I wish it did, but it didn't.

There's a reason teachers assign homework. We're not a craven group that goes out of our way to say, "Look I'm teaching, they have loads of books to read. Can't help it if they don't." We are, universally, strapped for time. Classroom time is best served teaching new topics, not reinforcing old ones.

When would you prefer students read books for a literature class? During the school day, during lit class, taking time away from discussion/analysis? During the school day, during a study hall, taking time away from electives? In reading sessions before school/after school, taking time away from sports/extracurriculars and requiring additional costs? Or at their leisure, where their free time allows?

>If you already understand it, you don't benefit from solving more quadratic equations.

Yes, you do. Understanding is only the second domain, out of 6, in Bloom's taxonomy of learning. Application—properly using a formula to solve an equation, which you're probably actually referring to—is the third domain. And being able to use the quadratic formula to solve a problem doesn't signify that you know anything more than how to memorize a formula and plug numbers into it.

There are some incredibly bright students out there who can master a concept in a single lesson without reinforcement. You might be one of them. I was. That doesn't mean all students are like you. Most of them require more practice than can be given in a single class period to master a topic. Some "get it" in the class period, and require practice to cement it in their memory. Other think they get it, struggle with the homework, and then get the help they need the next day. Every student is different.

>You end up testing which kids have peaceful homes, and parents who care. Some kids just can't do any homework with the home environment they're given. School should be such that it doesn't matter if your parents are drunks or academics.

That would be nice. Unfortunately, it's impossible. Family life affects far, far more than just whether or not students do their homework. It's hard to get a student from a loving home whose parents don't care about <subject> to care about <subject>. It's hard to convince a student who doesn't have a safe, secure, loving home life that literary analysis is worth studying. It's hard to convince a junior who got a job at Starbucks and is making more money than his parents ever did that finishing school is important.

>Totally fine with doing like in University: here's a mega list of interesting things related to the subject, go and browse around, get a feel for what the landscape is like. Come back more interested.

But K-12 is not University. We educate young folks, the same people we don't trust to vote, drink, smoke, or choose whether or not to attend school in the first place. The same people who pay through the nose for car insurance when they can drive. K-12 students are not good at weighing short-term and long-term decisions. Their brains aren't fully developed.

Given the option to not do homework with no obvious penalty, most of them… won't do homework. I ran a junior/senior Precalculus class once with optional homework. Some students did well on the assessments. Some did not. Many more than usual failed. Perhaps unsurprisingly, test grades correlated strongly to homework completion. Failing a test did not encourage students to study more in the future.

Halfway through the year, I put an end to the experiment and required homework. Test grades and student understanding improved.

It's our responsibility as teachers and as the adults in the room to ensure a student learns. It could be an excellent life lesson for a student to fail a high school class because he or she did not do the homework. You might be okay with that. I'm not. The end result is that the student has spent a year in a classroom and has not learned the material, which will have cascading consequences on that student's education. That's a lot to trade for a life lesson.