

I want to add to the other good answers that DoE is also responsible for enforcing special education in schools, along with all other protections against discrimination and support for low income families. This in particular helps red states more, usually, and is a big reason Congress hasn’t acted when Reagan took office and had a hate boner for the department.
As the resident education PhD in the room, I’ll just reiterate that this is bad, although it’s complicated and it sounds like a lot of the mandatory things (e.g FAFSA for college) would be moved to Treasury or other departments. It’s not as bad as getting rid of schools entirely, and it does have the added benefit of defanging Trump’s education goals. Just, you know, there won’t be transgender kids playing in girls sports if there’s no girl’s sports anymore since schools aren’t required by the feds to have it.
The biggest blow will mostly be in civil rights and in research, honestly. Civil rights because it’s funding is used as leverage to get schools not to discriminate on race, class, gender, etc, in so much so that you could even say sexual abuse under Title IX prevents teachers from diddling the kids. IDEA is also under them (that’s the disabilities bill for schools) so you may see less or no additional assistance for people with autism, intellectual disabilities, etc… In about a decade or two will actually lead to more crime and incarceration as education has a direct effect on reducing poverty and giving people purpose.
As you research, the DOE is a major contributor to education research, much in the same way as CDC was for health. I got my dissertation done using their data, and it is solid. They also provide grants to thousands of projects, and you can thank a lot of advancements in education to it, like improvements in pedagogy and establishing importance of after school programs and such. The system had some flaws, like rewarding grants based on established people only and ignoring young progressive researchers, but it was still better than nothing.
I think whatever damage he does can be undone and the department can be made better than it was because even I admit there’s bloat and the current system could be a lot better if it wasn’t so entrenched in neolib values. Lots of bullshit accountability stuff, similar to how we require hoops to jump through with welfare. Just, in the short term, it’s going to be extra hard for parents in red states and rural counties in particular because they receive the most aid from the department.