Privacy Policy

Last updated: 20 October 2026

This service helps students practise and learn. We keep the personal information we collect to the minimum needed to provide it. This page explains what we collect, why, and your choices.

Information we collect

Account details — if you create an account, your username and a securely hashed password. In class mode, a teacher may add a student name and PIN.
Anonymous session — a session identifier so open practice works without an account.
Learning activity — questions you view, answers you submit, marks, and your progress and points across lessons, coding and vocabulary. In the coding lessons we also keep the code you run, what it printed, its error messages and the hints you receive, so your teacher can see where you got stuck and we can improve the lessons.
What you do on each page — which pages you open and for how long, what you click and how far you scroll, and your learning actions. Generic field-use logging records length and interaction counts rather than typed text; answers and code submitted for learning features are handled separately. Never passwords: password fields and one-time codes are skipped on your device and dropped again on our server. Your teacher sees this for their own students, and we use it to find the pages and questions that are not working well.
Time on the site — the minutes you spend actively working, per section.
AI feature content — text you enter into marking, hints, the AI help button, the chat partner and code tools, so the service can respond.
Technical data — a one-way salted hash of your IP address in our application analytics, the coarse country derived from it, and a basic device/browser type. Hosting access logs can contain IP addresses. Google Analytics may also receive usage and technical data when its tag loads, as described under Cookies.

Anonymous product statistics are stored as daily counters for up to 90 days: coarse viewport size, browser/OS family, display and browser language, focused time, interaction counts, performance buckets and preloading use. These counters contain no account IDs, cookies, IP addresses, raw URLs or input text and cannot be joined to your learning records. Older activity records follow the retention periods below.

How we use it

To provide the service, mark your work and give feedback.
To save your progress and sync it across your devices when you are signed in.
To keep the service secure and reliable.
To understand overall, aggregated usage so we can improve.

Leaderboards

The all-time and online boards show places and lifetime earned coins. Eligible leading places display account usernames; lower places, zero-score accounts and small boards hide names. The online board includes accounts seen within the last 75 seconds. Public rankings do not show classes, locations or exact last-seen times. Your own position and emblems are available privately.

AI features

To mark answers and generate hints, replies and examples, the text you enter is sent to our AI model providers for processing, and is used only to deliver these features.

Where your data is processed (cross-border transfer)

The service runs on servers in Singapore, outside mainland China. Text you enter into an AI feature is sent to the model provider behind that feature:

When you use exercises.com.cn, your requests first reach a Tencent Cloud relay in Shanghai (TLS termination and a cache of static files only) and are then forwarded to Singapore; where your data is processed does not change.

Google (Gemini models, processed outside mainland China) — the AI chat partners, code hints, lesson answer checking, the writing coach, marking of written practice answers, exercise-sheet generation and automatic replies in the feedback window.
Alibaba Cloud (Qwen models, processed in mainland China) — practice-question hints, solutions and examples.

So if you are in mainland China, using some of these features involves a cross-border transfer of the text you submit. We send only the content needed to produce the response; your password is never sent (it is only ever stored as a salted hash). If you would rather your text was not transferred abroad, simply do not use those AI features — browsing, reading handouts and multiple-choice marking all happen on this site without any AI call.

Cookies

We use cookies for sign-in/session, language preferences and first-party traffic measurement. In production, the site also loads Google Analytics when enabled, except when the browser reports one of the configured mainland-China timezones. This is a timezone check, not a guarantee of your physical location. Google Analytics can set first-party analytics cookies, including `_ga`, to distinguish browsers and sessions, and sends usage data to Google. Browser cookie and tracking controls can restrict this collection.

Students and minors

This service is intended for school students. If you are under the age set by your local law, please use it with the knowledge and consent of a parent, guardian or teacher. Open practice never requires your real name.

Computer-lab sessions

When a teacher runs a live lab session, the site records the class's page state during the session (whether each student is in full screen, and when they switch windows) and, as the teacher chooses, captures the site page or a screen the student agrees to share. Only that teacher can see the captures; they stay on our server and are deleted after 24 hours. Students are told this when they join. Messages and files shared in a session are visible only inside that session. Questions students ask the AI tutor during a session, and its replies, are shown to that teacher.

Sharing

We do not sell your personal information. We use AI and hosting providers to operate the service, and Google Analytics to measure usage when its tag loads. We may disclose information where required by law.

Security and retention

Passwords are stored as salted hashes. Our application analytics stores salted IP hashes; hosting access logs can contain IP addresses. We keep learning data while your account is active and will delete or anonymise it on request.

How long the rest is kept: what you do on each page, 180 days if you have an account and 30 days for an anonymous session; lab-session captures, 24 hours; the application request records used to measure traffic, 90 days, after which only daily totals remain. Your progress, marks and points are kept while your account is active, because they are what your learning record is.