Science of Learning Institute

Principle 01 · Working memory

Working memory is small

Evidence grade: StrongLab evidence is deep and consistent; it explains why most other principles here work.

Reviewed

The 60-second card

The finding

Students can hold only about four new pieces of information in mind at once. Overload it and learning stops.

Do this

Teach new material in small steps, with practice after each step. Remove anything that competes for attention while new material is taught.

Best evidence

A major review of memory research found the real limit is about three to five chunks, not the "seven, plus or minus two" many teachers learned (Cowan 2001(opens in a new tab)).

3 to 5

chunks working memory holds at once, not seven

The 5-minute brief

New learning has to squeeze through a small working memoryThe model every page on the site builds from
EnvironmentWhat students see and hear in class
Working memoryAbout 4 new items at onceFills up fast
Forgotten if not practiced
Long-term memoryNo known limitWhere knowledge lives

Source: Cowan 2001, on the limit of working memory

Why it works

Working memory is where thinking happens, and it is tiny. Long-term memory has no known limit. Once knowledge is stored and practiced, it can be pulled into working memory as one chunk, which frees room for harder thinking. That is why a student who knows 7 × 8 by heart can focus on the multi-step problem, and a student counting on fingers cannot.

What it looks like

Grade bandIn practice
K–2One new letter sound or number fact at a time. Model, practice, check, then add the next.
3–5Teach long division one step at a time with a worked example for each step before combining them.
6–8New vocabulary taught before a reading, not discovered in the middle of it.
9–12A labeled diagram explained part by part, not a full slide of text read aloud alongside it.

Common mistakes

  • Introducing new vocabulary, a new procedure, a new tool, and a group task in the same 10 minutes.
  • Slides full of text read aloud word for word. Students try to read and listen at once.
  • Assuming "they understood it in class" means it is stored. Understanding today is not remembering next week.

What a leader looks for in 5 minutes

  • Is new material broken into small steps, with practice after each one?
  • Is the board or screen showing only what is being taught right now?
  • Do students have the basic facts they need, or are they stuck on the basics while trying to do the hard part?

What we don't know yet

Working memory limits are measured in labs with adults and simple items. How the limit plays out for a 6-year-old in a busy classroom is less precisely known. The direction is clear; exact numbers for children are not.

Go deeper

Researcher
Nelson Cowan; John Sweller (cognitive load theory)
Translator
Carl Hendrick and Paul Kirschner, How Learning Happens

Also called: cognitive load, cognitive load theory

Grades and subjects

1 studies behind this page

Sources

  1. Cowan 2001, working memory (opens in a new tab)

    pubmed.ncbi.nlm.nih.gov