Filed under: tips | Tags: concept maps, conceptual superstructure, tricks, words words words
Bio students learn a lot of definitions. It’s important and it makes sense: if you want to live in France, it makes sense to know what une baguette is, and if you want to live in Scienceland, you should know what Caenorhabditis elegans is. That does not mean, however, that students should be studying definitions as such.
Think about how scientists learn. Scientists don’t learn new areas of science by studying vocab flashcards. They just see words used in context — in articles, in lectures — and by seeing how they’re used they learn how to use them. Note that I didn’t just write: they learn what those words mean. They learn how to use the words: in what situations, and to get what ideas across.
It might be a subtle difference, but it’s useful. Scientific language is just language, and no one really uses language as simply a set of words and their meanings. Try this: define please, as in , “Please pass the ketchup.” Even if you come up with a good definition, does it convey the role that the word please plays in your daily life?
Now define hydrophobicity. A glossary or dictionary might give you something like, “the property of being water-repellent; tending to repel and not absorb water.” Okay, that definition is correct. It doesn’t, however, tell you much about what kinds of things are hydrophobic, what makes them hydrophobic, or what any of the biochemical consequences are of some molecule being hydrophobic.
A better way of understanding the word would bring up its connections to some other terms — maybe nonpolar, lipid, micelle — and some typical contexts in which the word is useful — like in explaining the importance of some transmembrane transport proteins, describing how protein folding happens, and explaining how surfactants work. Flashcards won’t do any of that. Definitions in isolation don’t help you follow the connections among concepts, and they don’t help you form associations as memory aids.
So what should you do? My favorite trick is to make concept maps. I’ll write more about concept maps in future posts, but here’s the gist:
- Write your concept terms on a piece of paper or (better, especially if you’re studying in a group) a chalkboard. Don’t write in columns and rows; spread them out at random.
- Take one pair of terms and draw an arrow from one term to the other.
- Label that arrow so that the terms and your label-words form a sentence. Example: if your arrow points from nonpolar to hydrophobic, the label should read: …molecules are…. The relationship thus reads: Nonpolar molecules are hydrophobic.
- Draw as many of these labeled arrows as make sense. Not all term-pairs will have sensical relationships, but many, many will.
As you map out the key concepts in a textbook section, you’ll find that you’re clarifying your understanding not only of each concept, but also of how it all fits together.
Filed under: tips, video | Tags: conceptual superstructure, memorization, microbiology, narrative, structure and function, textbooks
This week the microbiology students are studying prokaryotic cell anatomy, so this is the week I spend a lot of time talking about Gram-positive and Gram-negative bacteria.
For the uninitiated, the nutshell description is that bacteria can be classified as Gram-positive (G+) and Gram-negative (G-) based on whether they retain a particular stain under the Gram staining process. Here’s a video. (I didn’t make it.)
Differential staining isn’t all that interesting in itself, but the anatomical differences underlying the differential staining behavior (and also underlying differences in pathogenicity and vulnerability to drugs) are. These anatomical differences come down to how thick is the peptidoglycan layer, whether there is a lipopolysaccharide layer, and stuff having to do with flagella. As always in comparative anything, they’re frequently laid out in tables (like this) and diagrams (like this) which appear in every microbio textbook there is.
Now, I do like textbooks, and I do like the figures and tables that summarize large amounts of information for quick reference. Where problems arise is in students’ tendency to zero in on them and spend all their energy memorizing them.
Scientists don’t memorize big lists of facts. Instead, they fit new facts into the knowledge they already have. In the case of G+/- bacteria, it comes down to what’s happening during staining.
When you add the first stain, the stain particles enter all bacteria. Then you add Gram’s iodine, which forms a complex with the stain particles. Then you wash the slide with alcohol, and the stain-iodine complex leaves some cells but not the others. The cells that retain the complex are G+, and the G- cells can be stained with something else.
That’s a narrative, and this business about particles entering cells, forming complexes, and then being too big to exit might remind you of other narratives. (Bananafish, anyone?) I know that my own brain takes better to stories than to lists, so I use this narrative to anchor all the facts I need to retain about bacterial cell-wall anatomy.
Like this: Is it G+ or G- that has the thicker peptidoglycan layer? Well, it’s the G+ that retains the first dye, so it’s the G+ whose cell wall is impermeable to the stain-iodine complex. It therefore seems that the G+ must have the thicker peptidoglycan layer. Here’s another: Which has the lipopolysaccharide layer? It turns out that the alcohol wash disrupts the LPS layer, and that disruption promotes permeability to the complex. So it’s the G- that has it.
Learning biology means learning a lot of facts, but it can help to connect them together. Form conceptual complexes. In this case, I grouped some facts about structure to some facts about function, and I used the narrative of the staining procedure to give me a handle on it all. Grouping facts into complexes reduces the sheer number of things you have to remember — and more important, it’s understanding rather than simply remembering.
