Privacy Policy

Everything below is either something you type in or something the course records as you work.

Your email address

Required. It identifies your account, lets you sign in, and is the address used for the confirmation email and for password-reset links.

Your password

Handled entirely by Supabase Auth, the authentication service behind the site. It is stored as a salted hash, never as text. It is never visible to us and cannot be recovered by us — a forgotten password can only be reset, not looked up.

A display name (optional)

Only so the app can greet you by name. You can leave it blank during onboarding, and you can change or clear it later in Settings.

Your timezone

Detected in your browser during onboarding and editable afterwards. It is used to work out which local calendar day your study belongs to, which is what makes streaks, active learning days and the countdown correct rather than off by a day.

Your intended SAT attempt (optional)

A test date you pick, or “Not sure yet”. It is used only to show how many days remain until that date. No date of birth is asked for at any point.

Your learning progress

Which chapters are available, in progress, completed or skipped; which guided tasks you have finished and how many hints you opened; your answers to practice questions and whether each was accepted; the active time each question took; and the saved calculator state from guided practice so a chapter reopens where you left it. This is what the course itself runs on, and it is what the My Progress page reports back to you.

Active-time heartbeats

While a lesson page is open and visible, the app sends a short signal roughly every 15 seconds so it can measure real study time. It stops when the tab is hidden or when you have been idle for about two minutes, so refreshing a page or leaving it open in the background does not inflate your numbers. It records that you were active, not what you were doing elsewhere.

Your theme preference

Light or dark. This is stored in your own browser (localStorage) and is not sent to or stored on our servers.

• No date of birth, postal address, phone number or government identification.
• No advertising identifiers, ad-network pixels or behavioural-advertising profiles.
• No third-party marketing or analytics trackers that follow you across other websites.
• No purchased or broker-supplied data about you from anywhere else.

Accounts and progress are stored in a Supabase-hosted Postgres database, with lesson media held in Supabase Storage in a private bucket. Every table has row-level security enabled, so a signed-in account can read and write only its own progress rows.

The site itself is served by a web hosting provider, which — like any web server — processes ordinary request information such as your IP address and browser user agent in order to deliver pages and to protect the site against abuse. That is operational, not marketing.

Supabase and the hosting provider act as processors: they hold and serve the data so the course can run, and they are not permitted to use it for their own purposes.

The only cookies this site sets are the authentication session cookies created by Supabase Auth when you sign in. They are strictly necessary: without them the site cannot tell that the person requesting a protected page is you. Signing out clears them.

Your theme choice is kept in your browser’s localStorage, and guided-practice calculator state is saved to your own account row so it can be restored on another device.

There are no advertising cookies, no third-party marketing trackers, and no cross-site analytics on this site. That is why you are not asked to click through a consent banner.

Your personal information is not sold, rented or traded, and it is not shared for cross-context behavioural advertising. It is shared only with the service providers named above that are needed to run the site, and only if we are legally required to disclose it — for example in response to a valid legal request.

Learn Desmos is intended for students aged 13 and older. It is not directed at children under 13 and accounts should not be created for them. If you believe a child under 13 has created an account, write to info@learndesmos.com and the account and its data will be deleted.

Account and progress data is kept for as long as your account exists, because that is what the course reads to know where you are. If you ask for your account to be deleted, it and its progress rows are removed. Backups held by the hosting services roll off on their own schedule.

Whatever your location, you can ask to:

• see what is held about you, and get a copy of it;
• correct anything that is wrong — display name, timezone and SAT date are editable yourself in Settings;
• delete your account and its data;
• reset your progress without deleting the account, from Settings; and
• object to or restrict a particular use of your data.

Depending on where you live, these may be legal rights under regulations such as the UK and EU GDPR or the CCPA, including the right to complain to your local data protection authority. We intend to honour requests either way, without charge, and will not treat you differently for making one.

Email info@learndesmos.com from the address your account uses, and say that you want your account deleted. We will confirm the request and delete the account, its profile, and its progress records. If you write from a different address we may need to verify that the account is yours before acting.

Traffic is served over HTTPS. Passwords are hashed by Supabase Auth and are never handled by this application in readable form. Database access is restricted per account with row-level security, answers to practice questions are held in a table that learner accounts cannot read at all, and lesson video sits in a private storage bucket reached through short-lived signed links.

No online service can promise perfect security, and this one does not either. What it can do is keep the amount of personal data it holds small, which it does.

If this policy changes, the revised version is published on this page and the “Last updated” date above changes with it. If a change materially affects how your information is used, we will make that clear rather than relying on the date alone.

Questions about this policy, or about any data held about you, go to info@learndesmos.com. See also the Terms of Use and the Disclaimer.