Organizing with nested collections

A collection can contain other collections. This lets you build a two-level structure — for example, a "Physics" collection with sub-collections "Kinematics", "Dynamics", and "Thermodynamics" — so you can reach any group of problems quickly.

The collection tree

The left panel shows all your collections as a tree. Click a collection's name to view its problems. If it has sub-collections, an arrow appears; click it to expand or collapse them.

On desktop you can drag a collection to a new position in the tree to reorder it or move it inside another. On mobile this action is not available; use the context menu to organize.

Breadcrumbs

When you open a collection, a breadcrumb bar appears at the top: My problems › Physics › Kinematics. Each part is a link; click any level to go back to that point without losing context.

Sub-collection cards

Just above the problems table, the app shows cards for the sub-collections inside the current collection. Each card displays the sub-collection name and how many problems it contains. Click a card to open that sub-collection.

The problems table

Inside each collection, problems appear in a table with columns for Status, Title, Difficulty, Topics, Type, and Source.

To search, type in the Search problems... field in the top bar. To filter, click Filters and choose the difficulty or status you want. To change the order, use the selector inside Filters: you can sort by Collection order, Most recent, Title, or Difficulty.

The table shows problems in the current collection only. Problems in sub-collections do not appear here; open the sub-collection to see them.

Multi-selection

You can select several problems at once using the checkboxes on each row. With multiple problems selected, an action bar appears that lets you delete them in bulk or move them all to another collection at once.

Frequently asked questions

Can I have more than two levels of collections? The tree supports up to two levels of nesting: a root collection and its direct sub-collections.

Does the search find problems in sub-collections? No. The search and filters apply only to the collection that is currently open. To search inside a sub-collection, open it first.

Can I reorder collections on mobile? Drag-to-reorder only works on desktop with a mouse. On mobile, use the context menu (long-press) to access the options for each collection.

Next step

• Collections — create, rename, and delete collections.
• Publishing to the Market — share an organized collection with other students.