That poster also isn't considering that we have taken more and more money out of education over the years. The average is 30-40 kids in a classroom PER teacher, how much can you expect?
If we prioritized education more and got the margin down to 10-20 kids per teacher, results would be much better.
The suggestion that a "mom stay home and teach her kids" stinks of racist privilege at its very core. That said, racist privilege is at the core of most conservative ideas about things.
Well at least it's not 60-100 kids per teacher, and two classes per classroom. Or hallway. Or under the tree and the students bring their own tables and chairs.