In most courses, you finish every lesson in one unit before moving on.

This can feel smooth because each new idea is close to the one you just learned. That fluency is useful early, but it can overstate how well you understand the material - if you return after completing the next unit, how many exercises from the first unit can you still solve correctly?

When interleaving lessons, you have to retrieve older knowledge and connect it to the new concept. This is momentarily more difficult, but it acts as an implicit review that consolidates your skills, making you more likely to remember the material long-term.

What if I don't want interleaving?

If you want to move directly towards a particular goal, or focus on one unit at a time, you can do that using Focus Mode. If you select Focus Mode, we'll still respect prerequisites and make sure you review older material when necessary, but we'll prioritize lessons that are more likely to help you reach your goal.

Demo