More on a recurring theme — Bret Victor has just posted “an immune response” to the Khan Academy‘s recent additions covering Computer Science and programming:

Here’s a trick question: How do we get people to understand programming?
Khan Academy recently launched an online environment for learning to program. It offers a set of tutorials based on the JavaScript and Processing languages, and features a “live coding” environment, where the program’s output updates as the programmer types.
Because my work was cited as an inspiration for the Khan system, I felt I should respond with two thoughts about learning:

• Programming is a way of thinking, not a rote skill. Learning about “for” loops is not learning to program, any more than learning about pencils is learning to draw.
• People understand what they can see. If a programmer cannot see what a program is doing, she can’t understand it.

Thus, the goals of a programming system should be:

• to support and encourage powerful ways of thinking
• to enable programmers to see and understand the execution of their programs

A live-coding Processing environment addresses neither of these goals. JavaScript and Processing are poorly-designed languages that support weak ways of thinking, and ignore decades of learning about learning. And live coding, as a standalone feature, is worthless.
Alan Perlis wrote, “To understand a program, you must become both the machine and the program.” This view is a mistake, and it is this widespread and virulent mistake that keeps programming a difficult and obscure art. A person is not a machine, and should not be forced to think like one.
How do we get people to understand programming?

I have nothing to add other than to tell you to go read the whole thing.
Previous/related posts:

• Khan Academy Tackles CS Education (Aug 14, 2012)

• Yes, Do Learn To Code! (May 15, 2012)