The first two levels I am very familiar with in my own reading, but I’ve never consciously done the last compression level. However when I go through my own Anki cards I will often give the answer in a much more compressed way than how I originally wrote it down, so it’s likely happening at some level during my memorization or reading process.
I'd never put any conscious thought into how I read until recently. It was helpful to define the stages, even though I assume they're familiar to most people. I want to write a separate post about something I think is the most important. Good reading is about making deliberate choices about transitioning between these three levels, with long-term strategy in mind. And that long-term strategy is something like:
A huge part of effective scholarship is knowing what you can ignore, either by not studying it at all, or minimizing the depth at which you study it, so as to minimize opportunity costs of your learning.
Putting the process of reading a textbook into words, and a practical framework, helped me, but I think this post did not offer as much value as the Jenga tower one you wrote previously, perhaps due the "obviousness" of this post's material (I do recognize that although this may not be helpful to me, it is helpful to others).
A year ago, I didn't have any conscious ideas for how to read a textbook. I was frustrated by forgetting things, and had heard about memory palaces. When I was playing classical piano, I was able to memorize long complicated pieces of music with thousands of notes. The nice thing about piano music, besides the fact that it gets your muscles and ears involved, was that I had developed a set of methods for breaking down a piece and learning it effectively. I didn't really have any equivalent for book-learning.
After experimenting with memory palaces, I found that they just weren't getting me where I needed to go, although the practice at visualizing has proved extremely valuable. This post explains how I read now.
Level 1: The "check OK" method
Many sentences contain information that makes plain sense. You might not know which bits are going to be important. You might not know the point it's trying to make yet. And you're not necessarily committing to trying to memorize it, or even take notes on it. But you get it. You read it, and you think, "mmm-hmm, OK." An example of such a sentence is:
"Glucose is the major carbohydrate fuel for many cells."
Whole paragraphs can be composed of sentences like this. They're either not telling you anything new, or else they're so detailed that you consider them to be beyond what you need to remember.
At Level 1, you're checking for that "mmm-hmm, OK" reaction, so I call this the "check OK" method of reading. It's a safeguard against bleary-eyed skimming, and it's also meant to help you when the textbook is trying to make a point that actually requires some deeper comprehension.
Level 2: Babble-reading
If you're taking a biochemistry course, these sentences might be new information to you. Hopefully, if you were using the "check OK" method, you had an intuitive feeling of not fully understanding. "The inhibition of glycolysis by oxygen" is a pretty complicated idea. You just learned about glycolysis. Inhibition of glycolysis... what does that mean? And where does oxygen fit into the picture?
You go on to see that this "makes sense." The textbook spells it out for you. But it takes some conscious mental effort to connect their explanation ("far more energy is derived from the complete oxidation of glucose than from glycolysis alone") to their original claim that the inhibition of glycolysis by oxygen makes biological sense.
It takes even more work to understand why the fact that that inhibition by oxygen, not being an active participant in glycolysis, should raise a question about the inhibitory mechanism. And then you need a moment to consciously predict that the book's about to tell you.
For me, there's sort of a "whoah, slow down" twinge that I get when encountering passages like these. I engage my brain, my memory, and I think about these sentences until there's a feeling of "yep, now it makes sense." And then I proceed. I can't explain how exactly my brain works to make sense of passages like these. I can only say that it takes a different and more active sort of conscious mental effort. It's sort of about letting my brain reflect on the passage freely until something gives. So I think of it as "babble-reading," where you're babbling ideas, questions, memories, and reading until it clicks.
You really don't want to do babble-reading on the whole textbook. It's much slower, and often is not very rewarding. And sometimes, it's not enough. You need...
Level 3: Optimizing.
Textbooks describe biological concepts in natural language. Here's another sample from the Anthony-Cahill textbook on biochemistry, dealing with lactate:
I often feel confused when I read passages like this. Even though I understand each piece of information individually, I have a hard time putting them together into a pathway directly from the text. If you were going to write this in A -> B -> C -> ... -> Z order, it would go something like this:
This has been rearranged to convey virtually all the same information, but in sequential order. It takes work to extract that sequential order from the original paragraph, which is hard to do when reading. It also takes work to find a way to convert the sequential order into sentences, so I like to use a shorthand notation like this:
In reality, I might simplify this further with the bits of information I think are crucial. I generally move straight from the original textbook prose to something like this:
In this format, I also find the material easy to memorize. It's compressed, in order, and contains just the bits I actually need to recall. Over time, you get so familiar with the association of NADH and lactate that you don't need to spell the whole pathway out.
Overall, this compressed form of note-taking reminds me of mathematical notation and formal theorem descriptions, which I also find much easier to memorize than the informal versions.
There are other ways to sequence and compress as well. I memorized the amino acids by creating four names:
GAVLI PMFYW ("Gavli Pmfyw") and SCTNQ HKRDE ("Scuttinque Hikerdee")
Because these amino acids are also in an order that corresponds to some of their chemical properties, it makes it even easier to understand their role when they come up later in the textbook.
I also memorized the ten steps of glycolysis by breaking the substrate molecules into interleaved patterns. For example: 2 hexagons, 2 pentagons, 1 split, 6 triose steps; the order of the -OH groups on glucose and fructose (down-down-up-down or down-up-down, D-DUD and DUD); the number of phosphoryl groups written like a telephone number as (011) 212-1110; and more.
This makes it quite easy to reconstruct the molecule, because the patterns are pretty easy for me to remember. I have to do some extra thinking to recall exactly what 3PG looks like off the top of my head, but without this approach I don't think I would have been able to memorize it at all.
In short, for the procedure I go through to at this level is:
I think of all this as optimizing the material for later review or memorization.
Conclusion
When I'm at my best, reading the textbook means skillfully navigating between these three levels. I will typically memorize the absolute bedrock processes that come up in a given chapter: the names of saccharides, the steps of glycolysis and gluconeogenesis, the 20 amino acids, and so on. I'll take notes for easy review, which also has the benefit of letting me avoid re-reading the textbook, which will be mostly just redundant information at that point. Whatever didn't make it into my notes I deem unnecessary unless homework (or real life) forces me to study it in more depth.
This gets me through my classes and gives me a sense that I'm learning a manageable amount. I can relax into my reading with a sense of purpose ("oh I didn't get that? Better babble-read. This seems important, better extract the pathway. Actually, I'm going to memorize this part."), but without feeling like I'm either missing things by skimming, or laboriously over-studying in far too much depth. I find that with a conscious, explicit framework for reading, I'm able to refine and improve the sub-skills and techniques over time.