Privacy Policy

1. Introduction

Locus is a mathematics learning platform for individual learners and for schools. This policy explains what we collect, why, who else touches it, how long we keep it, and the rights you (or your school and parents, for student accounts) have over it.

2. Information We Collect

2.1 Account Information

• Email address and username
• Password (stored only as an Argon2 hash; we never see the plain text)
• Account creation date and accepted policy versions
• Student status (set by you, your school's email domain, or a school sign-on)

2.2 Sign-in Providers

If you sign in with Google, GitHub, or Clever (school accounts), we receive your email address, name, and a provider account identifier. For Clever we also receive your school role (student or teacher) and district identifier, which set your account type.

2.3 Learning Activity

• Problems attempted, your submitted answers, correctness, timing, and hints used
• Ratings, streaks, and progress per topic
• Class membership and assignment work (visible to your teacher)
• During ranked play only: fairness signals — when the tab or window loses and regains focus, when a copy, paste, or drag was blocked, and when a print or screenshot key was pressed. We record only the kind of event and its timing, never what was on your clipboard or what you typed. These protect the leaderboard; a human reviews them before any action, and the only action is removal from the public leaderboard. Kept 90 days, then reduced to monthly counts

2.4 Technical Data

• A session cookie for authentication (httpOnly)
• Crash reports if the app fails: the error, page URL, browser version, and the last few clicks — kept 90 days

We do not run analytics or advertising trackers, we do not store IP addresses, and we do not build advertising profiles.

3. How We Use Information

• Authentication and account management
• Grading your work and tracking your progress
• Showing teachers their students' assignment results
• Ratings and leaderboards (student accounts are never shown publicly)
• Service emails: verification, password reset, class invitations
• Fixing crashes and preventing abuse

Student data is used only to provide the educational service. We never sell personal data, use it for advertising, or use student data for any commercial purpose beyond providing Locus to the school.

4. Students, Schools, COPPA, and FERPA

Locus is intended for users 13 and older; we do not knowingly collect personal information from children under 13 outside of school arrangements, and we do not ask for ages or birthdates. For participating school districts, the district signs a Data Privacy Agreement with us and authorizes accounts for its students of any age — that authorization serves as consent in place of the parent under COPPA's school-authorization provision. If we learn we hold data from a child under 13 without that coverage, we delete it.

For school-linked accounts, Locus acts as a school official under FERPA: student records are used solely to provide the service under the district's direction, are never redisclosed, and are deleted or returned when no longer needed. Student accounts are excluded from public leaderboards and public profiles, do not receive third-party video embeds, and their data can be reviewed or deleted at any time on request of the school (parents: contact your school district, which can request either from us).

5. Third-Party Services (Subprocessors)

We keep the list short and serve all page assets from our own domain. The services below are the only third parties that receive any data, and only what is listed:

• Cloudflare — hosting, TLS, delivery of our service emails (recipient address, username), and (on the signup page only) the Turnstile bot check
• Google / GitHub / Clever — only if you sign in with them
• Stripe — payment processing for optional paid subscriptions (never offered on student accounts). Stripe receives your email and payment details; we never see or store card numbers. Subscriptions include a 7-day full-refund window
• YouTube — optional help videos, shown to non-student accounts only, via the privacy-enhanced youtube-nocookie player
• UptimeRobot — monitors our status page; receives no user data

We do not share personal information with anyone else except as required by law.

6. Data Retention

• Account and learning data: kept while your account exists; deleted when you delete your account
• Crash reports: 90 days
• Ranked fairness signals: raw events 90 days, then compressed to monthly counts; problem-serve timestamps 7 days
• Email verification and password-reset tokens: deleted after expiry; send logs after 30 days
• Unaccepted class invitations: deleted after they expire (7 days)

Deleting your account removes your personal data immediately, including crash reports and problem reports you submitted.

7. Your Rights

• Access and portability: download everything we hold about you as JSON from your account (or via our support address)
• Correction: update your information in Settings
• Deletion: delete your account in Settings; removal is immediate
• School-linked accounts: your school can request review, export, or deletion on your behalf; parents can direct requests through the school

8. Data Security

• All traffic is encrypted in transit (TLS)
• Passwords are hashed with Argon2
• Session cookies are httpOnly and same-site
• Administrative access to student data is limited and logged

No internet service can guarantee absolute security. If a breach affects your data, we will notify affected users and schools without undue delay.

9. Cookies

We use one authentication cookie and your browser's local storage for preferences (theme, remembered username). There are no analytics or advertising cookies.

10. Contact

Questions about this policy or your data:

Email: privacy@locusmath.org

11. Changes to This Policy

When this policy changes we post the update here with a new effective date and show a notice in the app asking you to review it. Material changes affecting school-linked accounts are communicated to the district.