I saw another thread where someone was trying to learn measure theory without real analysis. Then someone mentioned about a ladder of mathematics, and how it doesn't really work to try to skip levels.
Does anyone have an example of what this ladder would look like? At some point, it would have to go both horizontal and vertical, of course. I think if each level had a few sample problems, that also helps set the stage.
Some steps are obvious. Single-variable calculus before multi-variable calculus before partial differential equations, for example. Does anyone have a full progression?