Imagine if Amazon had only one size box or if Wikipedia made you wait until next semester to read an article.

Conventional higher education is organized in terms of majors, minors, semester long courses, and prerequisites. There are plenty of good reasons for that but it doesn't necessarily fit with how learning actually happens.

Suppose a group of students are learning about 3D printing and they wonder why ABS plastic behaves different from PLS filament. The old answer might be "well, you should take a course in polymer chemistry." When the eager student pursues this lead she will find out that first she needs to take chem1 then chem2 then organic 1 and 2 and then she can learn polymer chemistry. In a word, that's not going to happen. An alternative is available: we can call up the chemistry department and ask if they have someone who could give a one hour