The problem is generally not that the concepts have been deleted from your brain, but rather that you are having trouble recalling them. Imagine an enormous room full of filing cabinets full of index cards. All the information you ever learned is on those cards somewhere. The problem is finding it.
Now, our memories are designed so that we remember the things that are most 'useful' for us to remember. Unfortunately, what our brain defines as 'useful' aren't necessarily the ones that help us pass exams. Rather, they tend to be the ones that our ancestors found valuable for survival. Going back to the room full of index cards - it's like you've got a quick reference book to help you find important cards, and your brain is constantly updating that reference book. Unfortunately, however, the part of your brain that does these updates is "stupid" in the same way that computers are stupid - it has no real understanding of the information on the cards. The best it can do, then, is follow an algorithm (albeit a clever one) that was designed to provide rapid access to the information that helped our ancestors survive.
What We Remember
As a result of this algorithm, then, our memories tend to work best for things that:
- Are useful to solve practical problems
- Are concrete examples of ideas
- Are Surprising or otherwise emotionally charged
- Relate to other things you know
- Were learned recently
- Are simple
- Have been experienced personally
- Have been encountered by a variety of senses
- Were learned in a similar context to the one in which you're trying to recall them
Embrace Good Teaching
Many of the tasks that are set by teachers are designed (at least in part) to get information to stick. By practising these tasks, we typically improve our ability to recall the things we're being taught. One of the main things to do when studying is to engage in these activities as fully and enthusiastically as possible.
For example, writing essays helps us structure our memories, gives us opportunities to build connections between ideas, helps us rehearse concrete examples of ideas, provides repetition, and so on. Similarly, practical exercises give us concrete experience, help us build mental pictures and provide multi-sensory experiences.
One of the benefits of your 4th year studies is that they will force you to go back and find the holes in your recall process, and help you to patch them. You should be able to use your notes and text books from previous courses to revise old concepts and get up to speed on them again. Of course, you may no longer have access to these resources, in which case you may need to insist that your tutors point you in the direction of some basic texts etc. from which you can re-learn the required concepts. You're more likely to get support in this if you (1) demonstrate that you're making an effort yourself, (2) ask very specific questions, and (3) show appropriate respect and appreciation.
Use Specific Techniques
There are also a variety of specific techniques that tap in to your recall mechanism to enable you to remember facts and lists etc. Things like mnemonics, word-association and so on. I'm not going in to detail here as I'm sure you can Google them for yourself.
Finally, there are a variety of factors that can recall. By eliminating these you're more likely to remember things that you need to remember:
- Alcohol and drugs (but don't stop taking prescription medicines without consulting your GP first)
- Lack of exercise
- Poor nutrition or hydration
- Lack of motivation
See the Big Picture
Don't be overly concerned with forgetting things.
Learning specific facts and concepts is only one of the benefits of study. Whilst this is immensely valuable, there are other, even greater benefits: thinking skills, the ability to apply our learning, the chance to develop our own way of looking at the world, the opportunity to discuss ideas with other people, life-long study habits... let alone the whole social and life-experience side of things.
Consider this: many of the things you learn today will be of little use in your future career. That isn't to say that they aren't worth learning. Indeed, the learning process itself is invaluable, and many of the concepts behind what you're learning now will be transferable to other situations in your future. At the same time, however, you needn't be too concerned if some of the ideas slip away, as long as you can keep up with the rest of your studies and as long as you can pass your exams and assessments.