Remembering is generally viewed as consisting of three stages: 1. Acquisition or encoding is learning the material in the first place. 2. Storage is keeping the material until it is needed. 3. Retrieval is finding the material and getting it back out when it is needed.
Besides having a rapid forgetting rate and being easily disrupted, short-term memory also has a limited capacity, around seven items for most people. (This capacity has been found to be about the same for elderly adults as for young adults, and for people in oriental cultures as for people in western cultures.)7
This demonstration can also be used to illustrate the rapid forgetting rate of short-term memory. Instead of repeating the digits as soon as they are read to you, wait for 5 to 10 seconds to repeat them. If you do not rehearse the digits during this delay, you will find that the number of digits you can remember decreases considerably.
Similarly, students who criticize school exams because they forget most of what they learn soon after the exam are basing their complaint solely on recall. It is interesting to note that some of these same students may complain that a certain course is a waste of time because they have had the same material in another course. This suggests that they have not forgotten the material because they can still recognize it.