What does it mean to "understand"?
That's the core question of a video from Prof. Lemeshko I've recently watched. He is a theoretical physicist at the Institute of Science and Technology Austria (ISTA) near Vienna, and sometimes brings up pretty interesting topics in his videos that are not necessarily physics related, but rather more about general scientific stuff.
This one was very interesting, because it touches a topic that all of us have encountered throughout life. Whether it's when we read about something, listening to a presentation, or just listening to the teacher/professor giving a talk. We learn new stuff pretty much every day, although at a certain point is already known to us. But do we understand it?
Nowadays, I often encounter this in my job, when I have to explain stuff to colleagues, students, or even strangers. When explaining something, it's not sufficient to just know it, I have to really understand it. And this literally means understanding it and not just reciting something someone else has said.
Though it's not that easy to distinct between knowing something and truly understanding it. Like Prof. Lemeshko points out in his video, we tend to blend our present knowledge in with the new things we hear or read. Doing this creates the illusion that we might have understood what we just heard, because it seems familiar and thus known to us. However, this is often not the case, especially when we have to retrieve that information after some time (couple of days or weeks).
I especially remember this from school and also know it from a couple of people I know. When something new isn't practiced often or well enough, it's not really understood. While we didn't entirely forget it and basically know what it is, we might not be able recall and use it later on. This is for example while some people tend to struggle with mathematics, because if you didn't understand something early on, you cannot retrieve it later when it's a necessary basis for something more advanced. So we have to constantly retrieve the information by practicing it, in order to really understand it.
Prof. Lemeshko also backs it with some examples from university teaching and research. He says a common saying is that you haven't fully understood something until you've teached this topic for an entire semester. And this does make sense, because in order to teach it, they have to prepare the lecture. They create presentations and learning material, talk stuff through and not just think about it, so they see where they stall, and see which parts they don't understand well enough yet.
Towards the end, he shares an interesting study called The Critical Importance of Retrieval for Learning. In this study they observed various groups of students learning a foreign language. Some of them learned all vocabulary, regardless of whether it's new or not, others only learned the new ones. And they were repeatedly tested in a similar fashion, so either being tested with all vocabulary or just the newly learned ones. This combined into four groups they observed over multiple trials, until they learned all the new words.
The key point however is when they had to recall their knowledge on a final delayed test. In this final test, the students who had to constantly recall all the new words performed significantly better than the ones who only had to retrieve a portion of the total words. It very well shows how important it is to retrieve knowledge over and over again in order to understand and remember it. And it also shows the importance of regular tests. While certainly not all students like them, they are a good tool when it comes to learning and understanding.
