orgetting new words learned is very common and natural. Remember, at first it is fast but it tends to slow down over time. Remember, it can happen at the end of a whole period, as it can be after short learning (until a dersten elapses). According to calculations made, 80% of the learned knowledge is forgotten within the first 24 hours, but then this rate is decreasing.
The results of some studies on Spanish learners in English language show that during the first 3-4 years when there is no use of language, forgetting occurs but then forgetting is diminishing. There are two factors that determine the keeping of words in their minds. The easiest of these is the easier recall of words that are easy to learn. Another determinant is that words that have been spread over a long period of learning are learned more easily than words that are trying to be taught in a short time.

This is parallel to the principle of distrubuted practice (Thornbury, 2002: 26). Remember, it can be caused by later learning, by hitting the former, or by inadequate re-doing. One thing to mention about kicking is about overloading. During these surpluses, it may be that the old learned words are forgotten instead of old ones. This can happen, especially if the recently learned words show similarities to those learned previously.
Newly learned words also have features such as being based on the earlier ones (Thornbury, 2002: 26).
Repetition is the most important factor in remembering. Surveys show that repetition of learned information intermittently reduces the rate of forgetfulness.
This repetition mentioned is nothing more than vocalizing the words or re-reading the parts they pass through. Such a repetition should be in the form of reinforcement of the meaning of the word with more different examples, and therefore the meaning deepens in the mind of the learner. Researchers show that learning can be more effective if the student repeats the word he or she has learned in a different setting or environment than the one he first met (Thornbury, 2002: 26).