[smitty1e]

Therein lies the rub. Treating abstract and the concrete in isolation was always tough sledding for me.

Bouncing between the two is where the action is.

And units: if I had it all to do over, I would pore over the units sooner rather than later.

[pbronez]

Absolutely. Units are such a useful idea.

I was recently struggling to model a financial process and solved it with Units. Once I started talking about colors of money as units, it became much easier to reason about which operations were valid.

[kqr]

Strictly speaking this is about dimensional analysis, not units. (When discussing curricula we should be precise!)