Is your feature request related to a problem? Please describe.

Oppia currently has a classroom page for Math lessons, which is featured prominently and accessible via the home page, navigation bar, community library and learner dashboard. We would like to launch lessons in other subjects as well, but we cannot publish those lessons because there is nowhere to do so.

Describe the solution (or solutions) you'd like

The aim of this project is to implement the infrastructure to display multiple classrooms (besides the current math one), and make it easy for learners to navigate to them. In particular, creators should be able to create new classrooms and edit them at the relevant URLs, and learners should be able to view topics and lessons within these classrooms.

Here is a list of specific deliverables to include:

• In the topics and skills dashboard, topics can be filtered by classroom, and the default sorting order for topics should be by when they were last updated.
• The topic editor page should show which classroom a topic is in.
• Whether a classroom is visible/hidden should be configurable on the classroom admin dashboard. Hidden classrooms should be viewable by curriculum admins and super admins, with a banner displayed across the top to point out that it is hidden. They should result in a 404 for all other users.
• Implement a new "classroom index" page at www.oppia.org/learn, with e2e tests. The page is gated behind a feature flag. If there is only 1 visible classroom, this page should redirect to /learn/{{classroom-name}}. If there are more visible classrooms, it should show a list of classrooms. If there are no visible classrooms, it should show a standard error message in prod mode, and tell the user that they can create a new classroom at /classroom-admin in dev mode.
• Implement a generalized per-subject classroom page and update the math classroom to use it, including the routing. The functionality for classrooms should be fully generalized so that there is no direct reference to “/math” in the codebase.
• Update the splash page and navigation bar to point to the new classroom index page if there is more than one classroom. (The existing behaviour of the site should be preserved if there is only one classroom.) Add e2e tests for this.
• Update the community library and learner dashboard to point to the new classroom pages, and add e2e tests for this.
• In the topic viewer page, show which classroom the topic is in.
• Implement the necessary analytics events for classroom usage (see the "Automatically-collected metrics" section of the PRD).
• Work with the Web tech lead to add new CUJs and launch the new classrooms page functionality. Remove the feature flag once the launch is successful.

All UI updates should work fully on mobile devices and be responsive, accessible and fully internationalized.

The implementation should include unit and acceptance tests to confirm both 1-classroom and multiple classrooms behaviour. Cases to cover include: (a) a single /math classroom, (b) a single non-/math classroom, (c) 2+ classrooms.

Describe alternatives you've considered and rejected

No response

Additional context

Here are the PRD and mocks for the project, which you can use as a reference.

This project requires a design document, which should cover (at least) the following:

• How to generalize the routing to multiple classrooms (ideally, this is handled in the frontend)
• How to efficiently determine which classroom (if any) a topic is in
• What backend changes are needed in order to remove any hardcoding of "/math" and generalize it
• Any corner cases that need to be tackled

Notes:

• New classrooms are created by curriculum admins using the dashboard at /classroom-admin. You will need curriculum admin permissions, which you can grant at /admin (see the Roles tab).
• From a product perspective, it's fine to require that a topic cannot be linked to more than one classroom. However, if the technical design depends upon this being true, then please take steps to prevent this from happening (e.g. erroring and refusing to save if the user makes a change that would cause such a state to arise).
• This issue includes changes to the learner dashboard, and the mocks above are based on the redesigned learner dashboard (see [Feature Request]: Learner Dashboard Redesign #18384). However, if the dashboard isn't ready in time, it's fine to implement the new functionality on the existing learner dashboard instead.

Meeting notes: https://docs.google.com/document/d/1snAtIUn3s7kdMLg8UGp-7pd_69CZEN-OuO2aGaJAK_8/edit?usp=sharing

Journals: https://medium.com/@afzl210

Milestones

Sub-milestone plan doc.

Milestone - 1

Milestone - 2