Common questions.

We use the information needed to operate your account and study record: name, email, alias, academic year and group, answers, progress, statistics, bookmarks, and events related to friends and challenges.

We do not ask for a national ID, home address, phone number, payment details, or patient data. Administrators cannot view the original password. During sign-in, it is sent over HTTPS/TLS, and the server stores only a one-way password hash that cannot be reversed or read. Even if you reuse a password elsewhere, the SIRIUS team cannot extract it from your account. See the full Privacy Policy.

Students see the alias, avatar, and aggregate results only. They cannot obtain an email address or real name from the leaderboard.

Authorized administrators can resolve an account when required for support, safety, or moderation. Access is role-restricted and auditable. Read the design notes.

Yes. Enable Ghost mode in Settings. Your private progress and statistics remain saved, but your alias is excluded from the student ranking.

Use “Forgot password” on the login screen and enter the account email. If it is registered, you will receive a time-limited reset link. The public response does not reveal whether an address belongs to an account.

Yes. You can delete your whole account instantly from the Profile page (Danger zone section) after confirming your password, or send the request from your account email to admin@support.sirius-24.com. We may ask for a verification step before access or correction.

Questions are first filtered by the academic year, group, chapters, sources, and any other choices you selected. Each matching question then receives a hidden internal score that helps estimate its difficulty and your need to review it. The score considers active time spent on the question, correct and incorrect answer rate, attempts and performance changes, and how evenly correct answers are distributed across options; this helps prevent answer-position patterns from revealing the key.

The selector then samples from the filtered questions with weights that balance difficult or needed items with chapter variety. Shared cases and images stay together, duplicate copies are removed when duplicate filtering is enabled, and ordering remains reproducible within the same session while the score stays hidden.

Read the technical ordering notes.

No. It filters only the new study session. Editors explicitly tag alternate copies of the same item, and the filter keeps one deterministic representative per group. Database rows are not deleted.

Read the duplicate-filter notes.

You can generate a PDF from questions matching only the sources or chapters you selected. It preserves shared cases, images, and their order, and adds page numbers, a compact contents section, and a separate answer key. You can also enable duplicate filtering before export; a Bookmarked label appears only on your saved questions.

Read how the PDF is built.

Use Report inside the question and describe the problem clearly. The report enters an editor review queue, and reported material is deferred in fresh sessions while it awaits review.

No. The community page shows an aggregate count per question, not a list of the students who saved it. Read the bookmark privacy notes.

After adding an account as a friend, you can start a challenge with an eligible question scope. The server verifies participants and questions, grades answers, and computes the result; the browser cannot declare itself the winner.

Read the challenge lifecycle.

An answer is saved to local recovery state first, then synchronized to the server. When the connection returns, SIRIUS retries. If two devices change progress concurrently, version checks trigger a merge instead of silently overwriting one device.

Read the synchronization notes.