We use robust learning to refer to an outcome, that is, a desirable result of instruction. Robust learning is learning the achieves either or both deep conceptual understanding and strong procedural fluency. Sometimes instructional objectives of a course may put more emphasis on one or the other, but often both are desirable. Learning is robust if the acquired knowledge or skill meets at least one of the following three criteria:
• long-term retention: It is retained for long periods of time, at least for days and even for years.
• Transfer: It transfers, that is, it can be used in situations that differ significantly from the situations present during instruction.
• accelerated future learning: It accelerates future learning. That is, when related instruction is presented in the future, this knowledge allows them to learn more quickly and effectively learn from it(from The PSLC Theoretical Framework).
Instruction that achieves robust learning is designed so that the learning event space has some target paths that would cause an ideal student to acquire knowledge components that have either or both high feature validity, that is, they are accurate, deep, and general, and high strength, that is, they can be applied quickly and effortlessly.