The Feynman method is a useful way to identify any gaps in understanding of a concept and how to solve them:

  1. Select a concept.
  2. See if you can explain it in a way that a 5-year-old would understand.
  • If you can, rest assured that you understand it.
  • If not, there is one of three areas that you may need to address: understanding, memory and simplicity. Based on the area, consider the following questions:

3. Is there something you don’t understand? -> actively search for the information and understanding to fill this gap.

4. Are you having difficulty remembering certain parts? -> think of an analogy you can use which will make it easier to remember

5. Are you confident you understand and remember it but are having difficulty explaining it? -> think of a way to simplify the concept. Is there anything you can remove while still making sense?

I shall demonstrate this method using the example of how the kidney regulates blood pressure.

1. Select a concept.

How the kidney regulates blood pressure. So far, so good.

2. See if you can explain it in a way that a 5-year-old would understand.

The explanation to a five-year-old would be something along the lines of: “Our body stores lots of water. In the water, there is a lot of salt (like the salt you put on your fish and chips). Wherever the salt goes, the water follows. High blood pressure means you have too much water in your body. When this happens, the kidney gets rid of salt and water follows it. This goes into your bladder and later you wee it out. When the blood pressure is low, what does this mean? (you have too little water in your body) So what do you think the kidney does? (holds onto more salt so less water is peed out)”

Note: It may not always be necessary to appeal to a five-year-old’s toilet humour… but it can help.

3. Is there something you don’t understand?

Let’s say this explanation makes you realise you don’t understand how the kidney gets rid of salt. You would then consult notes on the mechanisms used. Even if you do not remember all of the specific mechanisms, having learnt deeper will make it more likely that you remember the key surface concept.

4. Are you having difficulty remembering certain parts?

If you are not sure you will remember the concept, then you can think of an analogy. This can be quite abstract as long as it holds true as the main purpose is to help you remember things. For example, let’s use ketchup to remember how the kidney regulates blood pressure: When pressure is high (i.e. you squeeze hard on the ketchup bottle), lots of salty ketchup comes out, whereas when pressure is low (you squeeze softly) then much less does. (You could expand the analogy by saying that when the lid is on it causes hydronephrosis but let’s not over-complicate things here…)

5. Are you confident you understand and remember it but are having difficulty explaining it?

Let’s say we over-complicated our explanation by talking about ‘blood pressure’ which a five-year-old may not understand. This is something that we could simplify to talking about the amount of water in the body.

Think of a concept now and practise this method.

If you can’t think of one, here are some suggestions (in increasing difficulty):

  • How muscles move body parts
  • Antibiotic resistance
  • The Theory of Evolution