A long time ago in a philosophy of math class, our professor offered this problem: upon hatching chicks have to be separated by sex. Experienced poultry farmers

A long time ago in a philosophy of math class, our professor offered this problem: upon hatching chicks have to be separated by sex. Experienced poultry farmers know how to tell them apart from feel but it's not a process they can describe. The problem then was: how would they teach it to a new hire? The solution offered was that they have the rookie hold the chick in their hands and guess while the experienced farmer corrects them. This was a great example of how tacit knowledge is acquired.