In the early chapters Ahrens outlines the general form and method for taking notes for a zettelkasten, though he's not overly descriptive of the method and provides no direct examples.

In the middle chapters he talks broadly about learning research and how the zettelkasten method dovetails with these methods.

He does this almost as if he's a good teacher showing the student an outline of what to do and why, but leaving it up to them to actually do the work and experimentation to come up with their own specific methods of use to best suit their purposes. This allows them to do the work themselves so that they have a better chance of following a simple, but easy set of rules, but in a way that will allow them to potentially more quickly become an expert at the practice.

“The one who does the work does the learning,” writes Doyle (2008, 63) [Section 10.5]

In some sense, he's actively practicing what he preaches as a teaching device within his own book!

I think that this point may be actively missed by those readers who aren't actively engaging with and converting his ideas into their own and doing the work which he's actively suggesting.

Ahrens goes through a variety of research on teaching and learning as they relate to active reading, escaping cognitive biases, creating understanding, progressive summarization, elaboration, revision, etc. as a means of showing and summarizing how these all dovetail nicely into a fruitful long term practice of using a slip box as a note taking method. This makes the zettelkasten not only a great conversation partner but an active teaching and learning partner as well. (Though he doesn't mention the first part in this chapter or make this last part explicit.)

The forms of thinking, writing, and elaboration that go into creating permanent notes for a slip box are natural means of facilitating actual, long-term learning.

For deep understanding the elaboration method may be the best tool, but may not be the best choice for learning isolated encyclopedic facts.

By learning isolated facts do they really mean memorizing here? In which case, perhaps using mnemotechniques is the best way to create synthetic associative links by which to tie one's knowledge into their other mental frameworks of knowledge. If thought about this way one is really elaborating their knowledge in a synthetic manner instead of more naturally. Either way, you're doing some form of elaborating as a means of assuming the knowledge. Both forms are work, though slightly different.

Elaboration is thinking deeply about the meaning of what we've read, how it could inform or answer different questions, and how it can be linked or combined with other knowledge. It is one of the best-researched and most successful learning methods. While it seems to have some subtle differences, it sounds broadly similar to the Feynman technique and is related to the idea of writing questions based on one's notes in the Cornell note taking method.

Or, what might also be called elaboration.

Verbs do not change forms, and whether or not the subject is referential to outside context or explicitly within the sentence is optional.

DNA has a negatively charged backbone. The histones surface has positively charged amino acids.

Trade off between untangling DNA fibers for cell replication and accessibility for transcription and translation.