Later On

A blog written for those whose interests more or less match mine.

Maximizing benefits of Duolingo’s spaced repetition in language learning

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Anki explains well how two tactics maximize learning: active recall and spaced repetition. Quoting from that page:

Active recall

‘Active recall testing’ means being asked a question and trying to remember the answer. This is in contrast to ‘passive study’, where we read, watch or listen to something without pausing to consider if we know the answer. Research has shown that active recall testing is far more effective at building strong memories than passive study. There are two reasons for this:

  • The act of recalling something ‘strengthens’ the memory, increasing the chances we’ll be able to remember it again.
  • When we’re unable to answer a question, it tells us we need to return to the material to review or relearn it.

You have probably encountered active recall testing in your school years without even realizing it. When good teachers give you a series of questions to answer after reading an article, or make you take weekly progress-check tests, they are not doing it simply to see if you understood the material or not. By testing you, they are increasing the chances you will be able to remember the material in the future.

Spaced repetition

The ‘spacing effect’ was reported by a German psychologist in 1885. He observed that we tend to remember things more effectively if we spread reviews out over time, instead of studying multiple times in one session. Since the 1930s there have been a number of proposals for utilizing the spacing effect to improve learning, in what has come to be called ‘spaced repetition’.

Duolingo uses both active recall and spaced repetition

Duolingo structures its courses as a “tree” of skills, each skill shown as a disk with an icon. A skill has 5 levels, and after 5 levels the skill is completed (though you can do additional practice sessions if you want).

Each level comprises four to six lessons, typically six. Formerly, I would start a new skill and complete all five levels, then move to the next skill.

I finally realized that approach is bad because it undermines spaced repetition, which (along with active recall) truly solidifies learning. Active recall is built into every lesson of Duolingo, and Duolingo is also structured for spaced repetition. One obvious example of Duoling’s use of spaced repetition is how a mastered skill will occasionally, over time, be displayed as “broken,” to be fixed by completing a practice session.

The approach I had been using was counter to the idea of spaced repetition.

A better approach

The skills are displayed in rows on a language tree. When I finish a skill, I start a new available skill (a skill icon in color rather than grayed) by completing the first level in it. I keep 6-8 skills active, which amounts to skills in 3 or 4 rows (and perhaps not all skills in the rows are active because I haven’t started them).

I work sequentially through the skills I am currently working on, one level in each skill. That number seems to be about right: I return to the oldest open skill within a reasonable period of time to reinforce what I had learned earlier.

I work through the entire current set of 6-8 uncompleted skills (i.e., skills below level 5), completing one level in each skill before I repeat any skill. I don’t start a new skill until I complete one of the currently active skills.

The result is spaced repetition: I complete a skill level and move on to the next skill, returning later. Now that I’m doing it, I see that the levels seem to constructed with this approach in mind. My former approach amounted to cramming (as the night before a test), and that is not effective for long-term retention. Spaced repetition over time is.

I imagine most Duolinguists know this already, but I just figured it out and wanted to share it.

Update: Yep, this very approach was described in the Duolingo blog. Wish I had seen that post earlier. (Someone just sent me the link.)

Written by LeisureGuy

10 June 2020 at 12:14 pm

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