[Proverbs31]

It's frustrating for sure.

First, I'd strongly encourage you to actively internally work on reframing how you see this without subconscious negative assumptions like "lazy" and "difficult". Your child's behavior doesn't necessarily reflect either attitude (I do understand it's "difficult" to deal with, but have found, from my own slow progress , that viewing a child as "difficult" tends to fuel a lot of negative dynamics instead of problem-solving and connecting as a team).

My kids needed me to be actively sitting with them a LARGE chunk of the time. It is challenging when juggling other family and personal needs! But his behavior is age-norm for many, many kids.

You said you know he understands the work. So may I respectfully ask, why are you making him do this work then? It is very difficult, even as an adult, to do "busy work"--i.e., pages of stuff you already know. Is he bored? Would he like something more challenging and less pointless?

(I just had a, um, vigorous discussion with a teacher in a class I'm taking as an adult because, while I'm not literally absolutely perfect at the subject, I've accomplished what there is for this point and am ready to move on; he isn't challenging me enough. As an adult, I have the self-discipline to do the work anyway, trying to mentally game it up in more challenging ways, but after a couple months of this, something's got to give--I can't stand just stagnating.)

Confession: I've actually cried about it, as some attempts to communicate this need to him have failed. At home though, because I hate crying in public. At any rate, 9-yo's aren't the only ones with those feelings when frustrated and bored; they just don't have as much practice managing them.

Also consider learning style. It sounds like you're having him do workbook type work. That's great for some people--myself included--but is a very poor fit for others. Does he like the type of task but need a more challenging level? Or does he need to do more hands-on work? (one of my kids needs that; it's the polar opposite of my personal learning style, so meeting her needs there has been a huge learning experience for me!)

Would he like doing unit studies on topics that interest him?

One thing I've struggled with is feeling like the kids have to finish "that year's" work by grade/age, that grade-level book. That's an artificial expectation that I'd gently encourage you to examine, particularly at his young age (it's a bit different when you're in upper high school years and need to knock off college prerequisites to achieve other goals--but he's nowhere near that!).

If you are using some kind of curriculum, there's likely already quite a lot of redundancy built in (for example, in Saxon math, I skipped the last quarter or so of the 5th grade math book and my child thrived on moving ahead to the 6th grade book--this has been a common experience across subjects/curriculums for other homeschoolers). For that matter, it's not at all uncommon for classroom teachers to not complete every bit of textbooks. If you're concerned about missing content, look at the scope/sequence of the current and subsequent book; find the overlap. Use the overlap if a child needs extra practice; skip it if they don't need it.

Again, you describe him as knowing the material--so why waste his time plowing through content just because some publisher decided to include it? Tailor how you use materials, making them fit the learner rather than trying to shove the learner into a generic plan. The ability to do that is one of the great advantages of homeschooling! Good classroom teachers do that too, but they are constrained by the number of students and mandated hoops to jump through.

Given the established negative dynamic, I'd set aside the book work for now. Converse with him. Find out what he's interested in. Be interested in it too. Find resources for him to explore--library books, classes outside the home, friends with similar interests, games, etc. Encourage him to teach you about his interests. He might initially say nothing is interesting. That's ok. Accept that and engage him in activities that visibly engage him (possibly with smiles, but for some of us, when we're engaged in a flow state of learning, we might even be frowning as we puzzle solve ).