Consolidation: Making Learning Come Together

Let me present you with a scenario: Let’s say that, as a master teacher, you design and deliver the World’s Greatest Lesson. This gem of a lesson includes some short input sessions, both reading and lecture. Because of the short duration of the input sessions, you don’t overload your students’ short-term memory buffers. During the lecture sessions, you are brilliant, changing the inflection of your voice, using props to make abstract ideas concrete, and moving around the room, making eye contact with students to keep attention high. You have carefully selected the readings to tap into your students’ prior knowledge of the topic and add important new information. In addition, the texts are high-interest and are appropriate for your students’ reading levels.

In between the input sessions, you have carefully designed a write-pair-share activity where your students get up and move to find a partner, so they reap the benefits of individual processing, peer processing, and movement; a cooperative learning activity where they brainstorm ideas using an equal participation structure, then select their top idea using a voting structure, and finally share their idea out to the class; and a simulation activity which helps your students connect emotionally to the material. As a result of designing and delivering this incredible lesson, you have ensured that your students are highly engaged throughout and that they have worked with the important material in the lesson in multiple ways during the class.

Now, here’s my question: have your students learned anything from this gem of a lesson? You might be tempted to answer immediately, “Of course! It was, after all, the World’s Greatest Lesson.” Well, let’s pump the brakes on the self-congratulatory train a bit.

The fact of the matter is that, technically, your students have not learned the material from the lesson… yet. What they have probably done, given your masterful teaching, is form some solid memory traces due to their encoding of the material and events in the lesson. But, contrary to what most teachers believe, the learning itself (at least as defined by neuroscientists) does not happen during the lesson itself, but rather much later, when your students aren’t even in class.

I know, it sounds strange, but it’s true. The real learning takes place during what is called consolidation, and it’s crucial that teachers understand this process, as it has important implications for lesson and unit design.

Consolidation: What It Is and When It Happens

First, let’s define consolidation. This is the stage of learning following initial encoding, when the mental representations (“memory traces”) created during encoding get strengthened and added to long-term memory. Over the course of hours or even days, the brain reorganizes and stabilizes these memory traces, replaying the initial encoding experiences, making connections to prior knowledge, and filling in gaps. At a biological level, new connections are made between neurons, creating a new “mental map” of the material. Only when these physical changes occur do neuroscientists consider learning to have taken place.

OK, that’s what consolidation is, but when does it happen? I’ve already mentioned that it takes place over a period of time, long after the lesson is over. The process happens mostly at a sub-conscious level, and starts soon after the initial learning, but the key time for consolidation is during sleep, when no new external input is competing for the brain’s processing space. That’s right, we actually do most of our learning while we’re asleep!

Implications for Lesson and Unit Design

When we take into account the crucial role consolidation plays in learning, and when we take into account how long it takes and when it takes place, we are forced to draw some important conclusions that impact the design of our lessons and units. First of all, we should realize that learning takes time, and that trying to cram massive amounts of material into a single lesson does not do anything to speed up learning (in fact, it greatly reduces the amount learned).

But to take this discussion farther, we need to say a few words about massed practice versus spaced practice. Let’s say that a foreign language teacher has a set of thirty important vocabulary words to teach. Here are three different scenarios; which one will result in better learning?

    • Scenario A: The teacher teaches all thirty words in one day’s lesson, having the class practice for a full hour (I will refrain from any discussions of methodology here–let’s just assume that she uses a solid approach and that the approach is the same for each scenario).

    • Scenario B: The teacher teaches the same thirty words each day across three days, but only has the students spend twenty minutes on the words each day, using the rest of class time to teach other material.

  • Scenario C: The teacher teaches the same words for the same amount of time in three lessons, with another day’s lesson in between–for example, twenty minutes on Monday, twenty minutes on Wednesday, and twenty minutes on Friday.

OK, which scenario will result in the greatest learning? Scenario C, without a doubt. Scenario B will result in the second most learning, and Scenario A will result in the least amount of learning. The superiority of “distributed” or “spaced practice” (Scenarios B and C) to “massed practice” (Scenario A) have been proven in research over and over again. In fact, this is one of the most robust findings in the cognitive science literature.

Why is this the case? Well, you should probably already know the two key reasons. One reason that spaced practice beats massed practice has to do with working memory limitations. In massed practice, it is easy to overwhelm working memory, leading to less efficient work with the material.

However, the key factor involved in the superiority of spaced practice to massed practice has to do with consolidation. Spacing the practice out over a period of time allows the brain time to consolidate each practice session during “down time,” and especially during sleep. Each time the student returns to the material, he will be strengthening the connections he has already started to build.

Break It Up and Focus on Variety

So, what does this all add up to? Well, obviously, the take-away here is to avoid massed practice sessions. If you are a math teacher, don’t teach one type of problem and then have your students do a gazillion problems of that type for the rest of the class period. That approach will not result in good retention.

Instead, teach two or three different problem types during the lesson, with shorter practice sessions on each problem type. Then cycle back to these different problem types after a day or two of delay, review them, and have students work on them again in short, focused practice sessions. By spacing out the practice sessions, you give your students’ brains time to consolidate each day’s learning and then reinforce it when they return to it.