What is spaced repetition and why is it essential?

Spaced repetition is a learning technique that reactivates content at increasingly long intervals, just before it is forgotten. For example: a reminder at D+1, then D+3, D+7 and D+21. Each reactivation strengthens the memory trace and extends the time before the next lapse.

It is one of the most solidly validated learning methods. A meta-analysis covering more than 300 experiments shows that spacing out reviews improves long-term retention compared with massed reviews (Cepeda et al., 2006). Dunlosky et al. (2013) rank it among the 2 most useful learning techniques, along with self-testing.

In workplace training, the challenge isn't the principle but the execution: manually scheduling reminders for every employee is impossible at scale. The Cards Learning Routine® engine automates this schedule and adapts it to each person's level and progress through routine conditions.

See also: cognitive anchoring and the retention cycle.