Recall: The Engine Behind Anki
Build the real SM-2 algorithm that powers Anki and Duolingo. Schedule every flashcard by how well you know it and watch the intervals stretch.
What you'll be able to build
Build the real SM-2 algorithm that powers Anki and Duolingo. Schedule every flashcard by how well you know it and watch the intervals stretch. Along the way you pick up real, transferable Ruby skills, not just this one project:
- hashes as mutable records
- methods that update state in place
- float math with clamp
- conditional scheduling logic
- simulating a process over time
- rounding and formatted reporting
A course like this one
Yours is built from your own placement, so module count and depth will differ. This map shows what a intermediate-level Ruby learner building Recall actually gets.
- Module 1: Values, strings, and puts5 lessons
Builds the script for your recall.
- Module 2: Collections: arrays, hashes, and Enumerable5 lessons
Builds the module workflow for your recall.
- Module 3: Control flow, truthiness, and predicting output5 lessons
Builds the method that powers your recall.
- Module 4: Methods, blocks, and reading errors5 lessons
Builds the reusable class for your recall.
- Module 5: Classes, modules, and program design5 lessons
Builds the collection pipeline for your recall.
- Module 6: Shipping a reusable Ruby tool3 lessons
Builds the command-line tool for your recall.
How the lessons actually work
Every lesson has you predict what a piece of Ruby code will output before you run it, then run it for real in your browser and fix what you got wrong. Each module ends in a challenge gate with hidden tests, so you can't advance until your code actually works. The course closes with a capstone that assembles everything into Recall, and a runnable proof page tied to your own code.
Common questions
How long does the Recall: The Engine Behind Anki course take?
about 7 hours, across 6 modules and 28 lessons, at roughly 15 minutes per lesson. Your own course may run shorter or longer, since it's sized to your placement result, not a fixed template.
Do I need experience?
Some. This is an intermediate-tier Ruby project, so it assumes you're comfortable with Ruby basics and pushes past them.
How much does it cost?
$15 one-time, no subscription. The first module is free, so you can see exactly how the course teaches before you pay for the rest.