penombra

penombra is a paper notebook for Android tablets with a tutor inside.

You write with your tablet's pen. When you lift the pen and wait, the tutor reads the page and writes back on it, next to your words. Ask a question, work a problem, sketch something and ask what is wrong with it. It answers where you are looking.

On the page:
• Your handwriting and the tutor's on the same sheet. It can underline, circle, point an arrow, put a check or a cross, and draw a labelled figure.
• Your language. The tutor answers in the language you write in. Its handwriting covers English, Chinese, Spanish, Arabic, French, Portuguese, Russian, Japanese, Korean, Hebrew and 22 more.
• Create flashcards: ask the tutor "add to terms". Study them together, write your answer to the term and the tutor will give you a hint or review if wrong.
• PDFs and pictures. Bring a textbook, a paper or a photo into a notebook, write on it, and ask. "Explain this" next to a diagram works.
• Split view. Tap the plus at the bottom right and the screen splits: the PDF or picture on one side, your page on the other. The tutor sees both.
• Notebooks. One per subject, project or book. The tutor remembers each notebook's conversation and what you tell it about yourself, so "what did I write on Tuesday?" and "what does page 40 say?" get accurate answers.
• Your pace. The bolt in the sidebar sets how long the tutor waits after you lift the pen: 1 to 4 seconds, or off. Off means it answers only when you double-tap the page with the pen.
• E-ink compatible. penombra runs on e-ink tablets, Boox included, as well as on color tablets.

No account, no sign-in. Open the app and write. The first page of your first notebook is a short guide in the tutor's hand, and the question mark at the top opens it any time.

penombra writes with the pen; a finger scrolls and taps. Android 11 and up.