Our free apps are made for kids in Grade 2 and up and their grown-ups. Here is what happens when someone uses them or visits our website.

What the apps keep on your device

• No sign-up: the apps don't ask for an account, a name or an email address.
• Progress stays on this device: Addition X, Subtraction X, Multiplication X, Division X, Typing X and Memory X save progress and settings in your browser.
• Solar System X doesn't save progress or settings. Periodic Table X saves only your best quiz score and view settings, on this device.
• Memory X nicknames: a nickname is optional and picked from a word list. Kids can't type their own.
• Starting over: clearing your browser's site data, or using another device, starts over.

Where the apps are hosted

• Your IP address reaches the host: like any website, the host receives your device's IP address when a page opens.
• Host cookie: when a page opens in a browser, the host (Vercel) also sets one session cookie, __vdpl. It holds the app's version number, which is the same for every visitor, so the page keeps using matching files. It's normally cleared when you close the browser. (About this cookie: https://vercel.com/docs/skew-protection)
• Seven of our apps load the Grok Build platform script: Addition X, Subtraction X, Multiplication X, Division X, Solar System X, Periodic Table X and Memory X.
• What that script does: each of these apps loads grok.com/grok-app-builder/extensions.js. Each load sends the visitor's IP address to grok.com and lets grok.com store a short Cloudflare cookie (__cf_bm, about 30 minutes). The response also tries to set a 400-day grok_device_id cookie, which Chrome blocked in our test (other browsers not tested). The script also makes a remix-eligibility request without cookies.
• Browsers handle cookies differently, so grok.com may set cookies. grok.com is a separate service, and its own privacy policy applies.
• Typing X loads no Grok script. Its host still receives your device's IP address when the page opens, like any website, and sets the same __vdpl session cookie.

Our website and purchases

• Payhip: our website and store run on Payhip. Payhip's privacy policy covers purchases and visits to our Payhip pages: https://payhip.com/privacy. It does not cover our apps or grok.com.
• Analytics on our website: our Payhip pages load Google Analytics and Facebook (Meta) scripts provided by Payhip. Payhip's privacy policy describes its analytics cookies. Our free apps don't load these scripts.
• Other services on our website: our Payhip pages also load files from services Payhip uses, such as hCaptcha (spam protection), Cloudflare's cdnjs, Google Hosted Libraries and Adobe Fonts (Typekit). Like any website, these services receive your device's IP address.

Questions

• Contact us: k12summerworkbooks@gmail.com

Last updated: October 21, 2026. K12 Summer Workbooks.