What word means 'discrete piece of knowledge'?

In my understanding 'knowledge' is one of a group of nouns in English that is characterized as uncountable (meaning 'knowledge' should never be made plural).

If that is the case, is there a word in English that describes the concept of individual bits of known material that can be made plural?

In other words, if knowledges is incorrect (although there is apparently some debate over that), what can be used in its place?

Edit 1: So there has been a decent amount of input so far and I felt like I should clarify one thing. The concept I need to capture is more than just information or data. Those are more related to trivia and facts. The word I am looking for is a countable noun that encompasses more than a physical skill that can be trained and observed. It is more than a list of facts. It needs to contain the concept of a body of information that can be used for extrapolation. For instance, naming the individual pieces of an engine is facts or data; understanding how they interplay and how that can assist in troubleshooting is knowledge; being able to repair a cracked head is a skill. The first example (fact, datum) and the last (skill) are countable, knowledge is not. So if I have knowledge of a group of separate topics I have knowledges. If this doesn't actually clarify anything, please let me know.

Essentially, the question is "What is the word for a bit or unit of knowledge?" Fact describes a unit of a certain type of knowledge, but does not apply to all bits of knowledge. Is a recipe a fact? Is a surgical procedure a fact? Is an engineering drawing a fact? It seems there are bits or units of knowledge that are more complex than facts.

In 2007 Google invented a word, knol to describe a unit of knowledge more complex than a fact. Knol was also the name of the service. Since Google had to create a word, we can probably assume they first searched for an existing word and could not find one.

I would suggest "Datum". As a singular part of data, it is presumably discrete. I've seen it defined as "a single piece of information" in Merriam Webster. This seems fairly close to "discrete piece of knowledge".