When creating flashcards, sometimes it's most natural to practice a couple of closely related ideas together, at the same time. But this creates a problem: as you put more and more information on a card, the card becomes irritating to review and inefficient to schedule, since you have to remember a large amount of things all at once, and if you forget any of them, you have to repeat the entire card.

One solution is to create multi-line cards. This works well if the items form a set or come in a natural order, and you want to recall all of the items in the set given some prompt. RemNote will then let you mark off whether you remembered each item individually, and can test you separately on specific items that you're struggling with.

However, many things you might like to practice together don't fit into that pattern. For instance, consider these cards about types of games in game theory:

These form two pairs: a game is either cooperative or non-cooperative, and either simultaneous or sequential. Logically, these go together. But the natural question is not something like “What are the two types of games with respect to cooperativeness?” All we really want here is for the two cards testing the definitions of “cooperative” and “non-cooperative” to be shown together.

We can do better by creating a card cluster. First, we nest the cards under the same parent. Then we add the Card Cluster power-up using /cluster:

There's no hard limit on the number of cards that can be placed in a cluster, but if you have more than a few, it's probably time to consider whether you're really expressing the cards in the most effective way – most people are not good at keeping track of giant sets of information like this, even when memorizing it in relatively effective ways.

While the example above shows Concept cards, clusters work great with Basic and Cloze flashcards as well.

When any card in a cluster is shown in the queue, RemNote shows the other items in the cluster that come before the one being tested, in gray, and shows empty boxes representing the items that come after it. (Why not show the items after? In real life, if you try to list out all the items in the cluster, you probably won't have access to the items that come after the one you're on, since you won't have retrieved them yet. If RemNote showed them during practice, you might come to rely on them to produce the answer.)

So the first item in the cluster looks like this:

And the second like this:

When you practice with spaced repetition, RemNote shows only the cards in a cluster that are due. Since you'll still see the items in the cluster that come before the one being tested, you'll always have the context needed to answer the question, but you won't have to spend time providing answers to the items that you already know.