There are two elements to creating a long term memory.
The first is repetition. Repetition helps the brain decide what information is important and therefore worth embedding in the long term memory. The maximum teaching duration for a ‘repetition’, before concentration starts to diminish, is circa 18 minutes and three repetitions are required for a long term memory to form.
The second is the length of the gaps, or ‘spaces’, between those repetitions. This is the critical element that dictates if a memory is formed or lost. During those ‘spaces’ the brain has to be distracted from the learning task at hand. These ‘spaces’ help the brain start to encode information in the long term memory; they provide the ‘space’ for the chemical process to take place. If the synapses receive the wrong stimulus during these spaces, they will reset and the memory will not form.
So the basic structure of Spaced Learning™ is; learn, rest, learn, rest, learn.