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Science on Learning: The Limits of Memory

Tap into your students' three types of memory to facilitate better learning.

In my first article in this series we explored benefits classical educators can derive from interacting with cognitive science. There we examined the first of six systematically constructed principles for learning: that learning takes time and reflection. So, what we are thinking about is the best barometer of what we have the potential to learn. However, that leads to a second, essential question: how much can we think about at any given time? This leads us to our second cognitive principle in our effort to learn about learning: learning is enhanced when cognitive limits are respected.

Through extensive research exploring how the mind makes meaning of information, we currently have a pretty good understanding of the factors involved in the process. Below is a simplified version of the mind, which outlines the elements that must interact in order for learning to take place.

Figure 1: Simplified Image of How Learning Works

Our mind has three primary elements: sensory memory, working memory, and long-term memory. Each of these elements interacts with the others constantly. We are constantly bombarded by information from our surrounding environment and our sensory memory helps us stay sane by selecting only certain things to think about rather than constantly being overwhelmed. However, that is the extent of its role; as information is selected it moves to our other elements, which are more important in terms of practical application.

As information is selected it is sent to our working memory. Our working memory is very limited and can only work effectively with a few items at any given time. I refer to it as the bottle-neck of learning because it is the narrow funnel through which we must move information—stuffing too much into our working memory will hinder learning. Researchers have done a variety of studies that have given us a pretty good baseline of “how much.” Back in the 1950s we found that our working memory can handle about seven items, plus-or-minus two; more recent research (Cowan, 2010) rounds that down to four! Independent of what that number is, let’s focus on the essentials: it is very limited!

Our long-term memory, however, as far as scientific evidence has found, has no such limits—you simply cannot have too much stored in your long-term memory. And this is key for dealing with the limitations of working memory. In subsequent principles we will consider important ways to help move information into long-term memory so that it endures, while much of what we learn, like writing in the sand, will wash away. But focusing on principle number two: How should the fact that our working memory is highly limited impact our instruction?
What are some practical tips to help improve your child’s learning in light of this principle?

  • Be cautious about tasks that lack sufficient guidance.

Often students are given an assignment and expected to work in a highly unguided manner. This may often hinder their ability to learn, and learn well. For example, if I want my students to learn about the American presidency and I assign them a laundry list of steps, then my instructions are using up some precious space in their working memory that may very well hinder their ability for learning and remembering important aspects of the American presidency! When working on a task with a lot of steps, connect principle number one to help principle number two: festina lente! Slow it down to make a productive push toward deeper learning. Unless the process is your intended outcome, tackle steps one at a time so that our limited working memory can focus on learning the material rather than steps.

  • Ensure that learning activities are focused on the learning goals.

When creating assignments, don’t use a particular activity simply because it is your favorite or your students love it. Instead, let the outcome direct you to the appropriate learning activities by ensuring they are aligned. For example, requiring students to create a digital presentation can be very engaging, however, what is learned may often be about using the digital tool rather than the material. Each activity we choose has the potential to draw our attention to other stimuli, which will result in limiting our precious working memory space. Look for a clear alignment between what your learner is doing and what you want them to learn to keep that bottleneck of learning as open as possible!

Cowan, N. (2010). The magical mystery four: How is working memory capacity limited, and why? Current Direct Psychological Science, 19(1): 51-57. Available online: <>
Miller, G.A. (1956). The magical number seven, plus or minus two: Some limits on our capacity for processing information. Psychological Review, 101(2): 343-352. Available online: <>

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