Doug Lemov's field notes

Reflections on teaching, literacy, coaching, and practice.

04.25.23Show Call, Collectively Worked Examples and the Transient Information Effect

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If you want problem solving, make sure students are looking at the problem…


Cognitive load theory describes the relationship between Working and Long-term Memory during learning.

Understanding cognitive load theory and its implications for the classroom is one of the most important things teachers can do to improve their instruction. 

Cognitive load theory focuses us on understanding and addressing the importance of building Long-term Memory. Kirschner, Sweller and Clark define learning as “a change in long-term memory” for example. “If nothing has altered in Long-term Memory,” they point out, “nothing has been learned.” 

It also stresses the limitations of Working Memory–thinking we are aware we are doing. Working memory is powerful but small. Barak Rosenshine’s work focuses teachers on sharing new information in small steps, for example, and then giving students an opportunity to process and reflect on chunks of information briefly before then encountering another small dose of new content.

One of the most important and perhaps lesser known applications of Cognitive load theory is the “Transient Information Effect.”  Working Memory is powerful but its capacity is small, so when information that is important to a required task disappears it hinders learning because students have to both remember and think about/analyze it.

If you want problem solving and analysis, this is to say, it really helps to be looking at the problem. If we’re a group and you want us to discuss solutions, ideally all of us are looking at the same problem! If we’re looking at it we can constantly refresh our working memory about the details and thus use all of our cognitive bandwidth to analyze.

One easy way to apply this in the classroom is via the TLAC technique Show Call, which involves selecting an example of student work and projecting it to the class while discussion and analyzing. When students can see it they are best prepared to study it.

You can see Britt Carson of Memphis Rise doing that here:


Britt’s asked her students to write a short response describing how the potential energy of a book changes when it moves to a new position.  After they write she wants to have a brief discussion about the correct answer.  She starts by taking one student’s work and projecting it to the class. Then, starting at about :50 in the video, they discuss it.

Notice that as they discuss the original answer everybody is looking at the example. This is far better than Britt reading the example to the class because they can constantly refresh their working memory about what it says and use all their capacity to reflect on its strengths and weaknesses.  As they think about how to improve the sentence they can constantly refer back to what’s there.

But Britt is also easily able to direct students’ attention to specific parts of the answer by pointing or underlining. For example when she starts revising they can see and focus in on exactly the right part of the sentence.  Now they have a clear and specific picture of how to improve it, not just a vague sense of what they might do. Both the initial work and the mark-up are visible to students and she can constantly direct them to specific parts of the answer, as when she underlines the word “store.”

Finally, because students are looking at the same image on the screen that they have on their page, it’s easy for them to transfer what they learn and revise to the written page.

You can see something similar at work in this video from Julia Addeo’s math class at North Stat Academy in Newark.


Julia’s approach is both similar and different. Instead of starting by projecting a student’s written answer, she transcribes Hakim’s initial response and then the group gradually improves and clarifies it. But she’s projecting as the does this so students can see the full answer and the improvements each step of the way.  So for example, at the end, when Julia asks a student to refine her initial answer with a  clarification–they are not manipulating the x ‘axis’ but rather the x ‘variables’–her student can re-voice the entire revised answer clearly and easily. “Say everything you just said but with the x values,” Julia says, and the student can create a full revised answer in a complete sentence easily because she can see it!!  Because she can complete this summary with a lessened load on her working memory, she’s also far more likely to remember it.

In the end students are left with what we call a “Collectively Worked Example,” a single answer that represents the best thinking of the group. The model response they develop is better than what any single member of the class could produce on their own. What a powerful tool.

So… if you want to give students the opportunity to experience the full benefits of their own analytical abilities in thinking about classroom content and if you want them to be able to remember what they think about, make sure the object of their analysis is visible via Show Call or the slight variation that Julia uses, the Collectively Worked Example.

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