Physics Playground
Last updated: September 26, 2026Physics Playground is an interactive science education app. We collect what the app needs to work, stay safe and get better, and we never sell data. Google Analytics and Meta ad measurement are optional and run only if you allow them.
Physics Playground is made by KheniTech, a business registered in India. KheniTech is the data controller for the personal data described in this policy.
Email: contact@khenitech.com
You can contact us at any time to ask for a copy of your data, to correct or delete it, to object to how we use it, or with any privacy question. You also have the right to complain to your local data protection authority.
Grievance Officer: KheniTech's Grievance Officer handles privacy questions and complaints at contact@khenitech.com. We acknowledge complaints promptly and aim to resolve them within 30 days.
By default the app signs you in anonymously using Firebase Authentication, which creates a random ID so your progress can be saved.
A grown-up can instead sign in with Google or Apple so progress is kept on other devices. Firebase Authentication then stores what that account shares: an account ID, the email address (Apple may provide a private relay address instead) and, for Google, the name and profile picture link. We never see or store passwords.
The following is saved in Google Firebase under your ID:
This data is used only to run the app and keep it safe. It is never shared or sold.
When you ask a question, the question text is sent to Physics Playground's own server, which asks Google's Gemini AI models (through Google Cloud Vertex AI, part of the same Google Firebase service the app already uses) for a short, child-friendly answer. Google does not use these requests to train its models. Physics Playground keeps your question only if you save the answer or report it. Each account, including a guest account, can ask a limited number of questions a day. To run and pay for the service, we keep a record of each use — the time, whether it worked, the account it came from and its cost — for 30 days, without the question.
Pictures are made only when you tap Draw it!, which sends the question (and the lab it links to) to the same server. Each account can make a few new pictures a day. A picture is saved without any link to you, so the same question can show the same picture again for anyone.
Answers and pictures in Curiosity Lab are made by AI, so they can sometimes be wrong. To keep one picture per question, we store the picture and the short picture description the AI wrote, without any link to you.
Save picture saves a picture to your device (on the website as a download; in the apps through your phone's share sheet). Nothing is sent to us. On iPhone, saving to Photos asks for permission to add photos. Read it to me uses your device's text-to-speech; depending on the device and voice, the answer text may be processed by Apple's or Google's speech service.
If you use the microphone button, your device's speech service (from Apple, Google or your browser) turns your voice into text; depending on the device, the audio may be processed on Apple's or Google's servers. The app receives only the text, never the recording.
To understand and improve the app, it records how it is used: which screens you open, which labs you open, play and complete (and for how long), whether you use camera control, and what you do in Curiosity Lab (asking, pictures, saving, trying a lab) — never the text of your questions. Each record is linked to your account ID (for guests, a random ID) and your device type and app version. We keep the detailed records for 90 days, and after that only daily totals that identify no one. They are deleted with your account. We rely on our legitimate interest in running and improving the app.
Legal bases. Google Analytics and Meta ad measurement run only with your consent (GDPR Art. 6(1)(a)), which you can withdraw at any time in the app's Privacy choices (on the Progress screen) or via Cookie settings on the website. The app's own usage records and crash reports run on our legitimate interests (Art. 6(1)(f)).
Google Analytics for Firebase (apps, only if you allow Usage analytics) receives the same usage events described above, a random app-instance identifier and your account ID. It is never used for advertising, and we do not let it collect your device's advertising ID.
Meta (apps, only if you allow Ad measurement) receives app-install and app-open events and, on Android, your device's advertising ID, so we can measure which of our ads led to installs. On iPhone, Meta receives the install and app-open events without your advertising ID, together with Apple's SKAdNetwork, which reports only aggregated results.
Website (only if you accept): Google Analytics records the pages you view (without the web address's extra
parameters, except campaign tags such as utm_source), the referring website's domain, your approximate location
from your IP address, your browser and device type, the usage events described above and your account ID (for guests, a
random ID). It uses _ga cookies lasting up to 6 months. If you reject
or don't choose, nothing is recorded and no analytics cookies are set. The website's fonts are served by us, not Google.
Retention. Google Analytics keeps individual events for at most 14 months.
Every Curiosity answer has a Report button. A report sends us the question, the answer and the reason you picked (Wrong, Scary, Not for kids or Something else), linked to your ID. There is no free-text box.
To run the app and keep it safe, the two people who run Physics Playground use a private admin panel. It shows account details (for signed-in accounts, the email address and sign-in method), progress, saved and reported answers, error reports, usage records and Curiosity Lab usage (account ID, time, whether it worked, cost). Every time they open a saved or reported answer, and every change they make, is recorded in an audit log.
Our team also gets automatic alerts in our private Slack workspace: when a grown-up signs in for the first time, when an account is deleted, a weekly summary, and when Curiosity Lab has a problem or someone uses all of the day's questions. Alerts contain counts, the device type and, for sign-ups and the daily-questions alert, the account ID — never names, email addresses or question text.
With your permission (Usage analytics), the app also sends the usage events described above — screens, labs opened, played and completed, camera control, and Curiosity Lab actions, never the text of your questions — to Google Analytics for Firebase, so we can see what to improve. If you don't allow it, nothing is sent to Google Analytics.
Google Analytics is governed by Google's Privacy Policy: policies.google.com/privacy
When the app crashes or hits an error, we collect a diagnostic report so we can fix it. We use Firebase Crashlytics (by Google) for this.
Crashlytics is governed by Google's Privacy Policy: policies.google.com/privacy
Only if you allow Ad measurement, the Meta (Facebook) SDK tells Meta when Physics Playground is installed and opened, so we can measure how many installs our ads bring. If you don't allow it, nothing is sent to Meta. You can change this at any time in Privacy choices on the Progress screen.
On iOS, Meta receives the install and app-open events without your advertising ID, together with Apple's SKAdNetwork, which reports only aggregated, delayed results. We do not ask permission to track you across other apps and websites, and we do not access your device's advertising identifier on iOS.
On Android, if you allow Ad measurement, your device's advertising ID is shared with Meta for install attribution. You can reset or delete it at any time in Settings → Google → Ads.
The app offers an optional camera feature that uses your device's front camera to detect hand gestures for hands-free control of experiments.
The app keeps a few things on your device: your privacy choices, sound and display settings, the
last screen you used, and a random session number for the usage records. On the website, Google
Analytics cookies (_ga) are set only if you accept. We do not use advertising cookies.
Meta ad measurement (only if you allow it) is used only to count installs from our own ads.
Physics Playground is suitable for a general audience aged 13 and over and is not directed at children under 13. We do not knowingly collect personal information from children. Guests never enter personal information; signing in with Google or Apple is meant for a grown-up and stores only what that account shares (described under Account & Identity).
All data is stored in Google Firebase, which uses industry-standard encryption in transit (TLS) and at rest. Firebase Security Rules let only your own ID read or write your progress. Our safety-review tools run on the server, check the reviewer's identity on every request and record every time a saved or reported answer is opened.
If you signed in with Google or Apple, you can delete your account and all its data in the app: main menu → Delete account. Deletion is immediate. See how to delete your account for the steps and for how to ask us if the app is no longer installed.
Deleting an account removes its progress, saved answers, error reports, usage records, Curiosity Lab usage records and daily limits. Reports it sent are kept for safety review but are no longer linked to anyone. Data that Google Analytics or Meta received with your permission, and crash reports, are kept by those services as described above and are not linked to your name.
Without an account, contact us at the email below and we will remove your anonymous Firestore record within 30 days. Uninstalling the app also severs access to the data (your anonymous credentials are lost with the uninstall).
If you have questions about this policy or want to request data deletion, contact us at:
We may update this policy as the app evolves. The "Last updated" date at the top will always reflect the most recent version. Continued use of the app after changes constitutes acceptance of the updated policy.