Planning needs to be responsive to how the prior lessons went. You can't simply pre-plan a whole year and expect those lessons to be effective. Eventually, you can get close to that point, if you are lucky enough to teach the same subject for years. But much like you can't expect a standup comedian to perform someone else's routine effectively, as a teacher, each individual has to figure out what's effective for them. Teaching is dynamic and interpersonal.
Grading is not just a matter of right/wrong, even in fields like math, where questions can be given that have one correct answer. It's providing the student feedback on where their misconceptions were that led to an incorrect response. And of course, the most meaningful schoolwork assignments don't have a single correct answer.
This is one of the many things that I find so interesting about effective teaching.
Your students are forming a mental model of how something works. Your job is to help guide them to the correct mental model.
If their mental model goes wrong, you have to debug it: you need to figure out exactly what they've misunderstood (which could be anything, and could be from years before your lessons with them started) and help them correct.
Yep, done correctly, it's a lot like debugging. Although, maybe in reverse. When I'm debugging, I'm trying to learn from the infallible machine how my assumption of how my own code works is incorrect :)
Grading is not just a matter of right/wrong, even in fields like math, where questions can be given that have one correct answer. It's providing the student feedback on where their misconceptions were that led to an incorrect response. And of course, the most meaningful schoolwork assignments don't have a single correct answer.