A major part of this problem is teachers who treat "student knows something I don't (or aren't prepared to teach right now)" as a status challenge to be rapidly obliterated, rather than as an opportunity to encourage a student.

Many, many adults are extremely emotionally unprepared to accept the possibility that they may be wrong and a child may be right; they start from the assumption that this is an impossibility, and reason backwards from there.

Or, in the case where they do in fact know that the child is right, they nonetheless decide to prioritize asserting authority over demonstrating how a mature adult should handle being wrong. And thus do students learn bad examples of what to do when they're wrong.

On top of that the teacher has to juggle two tracks, the normal one and a special needs one. There has been a push for awhile to put mentally disabled kids in with their age peers and the teacher has to handle it, maybe with a low pay assistant.

Denmark did this about 10 years ago, the results pretty much speak for themselves: Everyone is frustrated with it, teachers, parents, students, as well as their special-needs counterparts.

Grades have been steadily decreasing across the board, while enrolment in private education has skyrocketed (private schools do not have to accept difficult students). The private education is particularly surprising as Denmark has a very strong tradition of public education, where private education was viewed as something for the "elites" of society (e.g. royalty), now it's becoming more and more common.

Yeah - this is on OP if that is the case. No teacher wants that and it's annoying for the ahead kids and the behind kids. Better to give them something tangential to keep them engaged but still gate on moving ahead with the mainline curriculum.

To be fair - maybe that's what the product mentioned should have been doing? You can focus on general problem-solving ability by giving talented kids hard problems with the amount of knowledge adequate for their level rather giving them more an more material and making the whole learning process less manageable.

"general problem solving ability" isn't a real thing. Proficiency in solving, for example, math problems, does not confer the ability to draw conclusions based on evidence in history class. If you require a kid who's already mastered fractions to simply do harder and harder fractions rather than allowing them to continue onward, they will become bored and distracted, and ultimately burned out or resentful of the education system

OK, not general problem-solving ability, but subject-specific problem-solving ability. And I don't mean more tedious problems, but rather those that require self-discovery of non-standard approaches while not relying on any knowledge from further grades. E.g. for maths Olympiad problems exist for at least as early as 3rd grade, it might be possible to figure out something for younger children too.

I don't see why would shouldn't make it a goal to allow more advanced students to learn at a more advanced pace. They shouldn't be held back by the other students

We'll need to get rid of grade system then and let students advance on different tracks independently for that. Might be a good idea, but nobody is going to redesign the whole educational system because someone made an app.

I think it would be better to have a system where teachers aren't required to synchronize knowledge between 30 kids and some source material; where each kid can excel at their own pace and the teacher helps them manage their goals rather than being the primary source of information