Memory.

there are three memory types:

sensoric memory - what we perceive, see, arrives there,

short-term memory - lasts up to half of a minute or as long as attention is focused on that memory part,

long-term memory - when someone wishes to remember something, it's important to wish for that. then to repeat many times words to remember, etc ... that's how 'memory trace' is formed & put into long-term memory. it's important to make breaks between attempts at remembering something, forming a trace, a key to memory. giving material to remember a structure makes it easier to understand ... it's also about trying to understand & understanding.

(to be continued, perhaps).

Source: [6].