It is normal to forget most of what is learned within a few days after leaning it unless it is constantly revised to keep it fresh in mind.
Reasons why people forget certain things.
WEAK ATTENTION:
The first cause of forgetting is not properly attending to what we wish to remember. The result is that the experience does not make a strong enough impression on us. We forget because we do not pay sufficient attention to what we remember in order to imprint it firmly on the mind. A good memory, therefore depends upon attention to what is to be time.
LACK OF REVISION:
Much of what we learn is forgotten almost as soon as we have learnt it. The little that remains after that is forgotten more slowly. Research have shown that after on hour, 56 Percent of the material which we learn is forgotten; but after nine hours only, a further 8 percent had been forgotten; after two day only, a further 6 percent and only a further 7 percent after as long as on month. In other words about 70 percent of the amount which was forgotten in the first month was forgotten in the first hour of the month.
INTERFERENCE:
Interference is most active when the interfering material is most similar to the material originally learned. Another way interference occurs is when what has happened previously interferes with what is happening now, work which precedes learning also tends to interfere with the retention of the learned mater. What happened before an experience cause us to forget as well as what happened afterwards.
WRONG FOOD:
I have come to discover that food plays an important role in our memory. Research have been carried out that people suffer because of what they eat.