Working memory constraints in the classroom
Working memory is the mental workspace where you consciously process information. It holds roughly 7 items (plus or minus 2) for about 20 seconds before they fade. When you read a sentence with embedded clauses, you feel the strain: your working memory fills up trying to track the parts until you reach the verb.
In learning, overload happens when the instruction presents too many new ideas at once. A student learning fractions for the first time might encounter: the concept of parts of a whole, the symbol notation, simplification rules, and comparison all in one lesson. Each new piece taxes working memory. The student never gets to consolidate the first idea before the next one arrives.
Designing to reduce cognitive load
Effective instruction breaks complex topics into smaller steps and gives students time to practice each step before moving on. Worked examples reduce overload because the student can focus on the solution process without also generating solutions. Removing redundant information (saying something both verbally and in identical text on screen) cuts wasted processing.
The goal is to free up working memory so students can use it for deeper thinking rather than just holding information. Once an idea moves to long-term memory and becomes automatic (like reading individual letters), it stops taxing working memory, and the student can tackle harder concepts.