How Your Brain Wants Information Packaged

Phone numbers are split into groups for a reason. Working memory holds only a handful of items at once, and grouping information into meaningful chunks lets a single slot carry far more than a single digit ever could.

Dual coding works around the same limit from another direction: pairing words with images lays down two retrieval routes to the same memory instead of one. Cognitive load theory explains what happens when you ignore the bottleneck. Material that is only badly packaged gets mistaken for material that is too hard.

Then there is interleaving, which mixes topics rather than blocking them. It feels worse while you study and reliably produces better results on the test, which is why it is called a desirable difficulty.

Read the full research: Chunking, Dual Coding, and Cognitive Load on Speed Learning Research.