Please add "bring back the slide rule". I've never used one, but I think graphical techniques (including the use of slide rules - multiplication can be done by addition if you use logs) helps you get a better feel for maths.

Programming is a separate subject. Computer driven data-analysis is also a separate art to mathematics, though a maths background helps understand it. But these aren't core maths.

"Computers are useless. They can only give answers" - Pablo Picasso