Working memory is our mental ‘workplace’ that holds the task relevant information for the short periods of time until we complete the task. It differs from a short-term working memory in that the information is not just stored passively, but it is being ‘worked’ or toyed with (various mental actions are being performed). Multiply 26 by 4 without writing it down. If you were not too lazy to try that, you were performing this math operation in your working memory a moment ago.
One way to describe working memory is in terms of storage capacity. The “magic number” for the information bits that we can hold in our short-term memory storage and then retrieve mechanically is 7±2 and we can actively use even less information bits in our mental workplace at the same time. Ask a friend to tell you a 7 digit sequence and try to repeat it straight after. You will succeed most likely. Now try to do the same, bus repeat the digits backwards. You will struggle much more and maybe even ‘lose’ a digit or two. Children as well as adults vary in terms of working memory capacity.
Another important aspect of working memory is updating - the process when we constantly follow the information stored in memory and change the old, obsolete information with new and valuable information. Given that working memory storage capacity is limited, the ability to effectively get rid of outdated information and replace it with new and relevant information is particularly adaptive.
It is easy to see that children are meant to rely on working memory heavily in school, whether they are reading, writing a dictated text, solving math problems or spelling a word. No wonder that working memory is the executive function, which is shown by numerous studies to be most closely related to academic performance.