Arca: Daily Learning 365
General knowledge every day
Free · In‑App Purchases · Designed for iPad. Not verified for macOS.
365 days of general knowledge, one short lesson a day. Science, space, psychology, nature, history and earth, told with everyday comparisons. Free for your first week.
Arca is 365 days of general knowledge: one short lesson a day, two or three minutes to read. Pick a genre and keep learning every day for a year, from why the sky is blue to how everyday things came to be. Each lesson comes with its own painting, and the day's lesson stays on your Home Screen as a widget.
ONE IDEA A DAY
Why is the sky blue? Why does the Moon always show us the same face? Why do we see what we expect to see? Each lesson starts from an everyday question and walks you to the mechanism with an everyday comparison. One clear idea per lesson, at a length you can keep up every day.
ART MADE FOR EVERY LESSON
Every lesson has its own cover and inline artwork that interprets the idea. Not a diagram: a picture you will want to keep on display.
THE WIDGET
The day's artwork fills the widget, with the date and the lesson title set in colors drawn from the painting (both can be turned off). Tap it to open that day's lesson.
Small, medium and large sizes, plus extra large on iPad.
A FREE FIRST WEEK
For seven days from installation, read one lesson a day from seven genres: science, space, psychology, philosophy, nature, history and earth. The lessons you open stay with you to reread.
365 DAYS OF THE GENRE YOU LOVE
Six packs are available now:
SCIENCE 365: physics, biology, chemistry and discovery.
SPACE 365: from the Moon to the edge of the universe.
PSYCHOLOGY 365: how minds notice, decide and remember.
NATURE 365: forests, oceans, the body and everyday wonders.
HISTORY 365: how everyday things came to be.
EARTH 365: climate, land, oceans and the systems that connect them.
The day you buy is Day 1, and a new lesson and artwork open every day. Lessons you have opened stay available anytime.
Each pack is a one-time purchase. Not a subscription, nothing renews.
Philosophy is in production and coming soon.
CHECKED FACTS
Numbers, dates and names are checked against sources. Where science has no answer yet, the lesson says so.
QUIET BY DESIGN
No account. No ads, analytics or tracking. What you read and your settings stay on your device.
Available in 10 languages: English, Japanese, Korean, Chinese (Simplified and Traditional), Spanish, French, German, Portuguese and Italian. Lessons are translated too.
Terms of Use: https://akiaki1984-alt.github.io/app-legal/arca/terms/
Privacy Policy: https://akiaki1984-alt.github.io/app-legal/arca/privacy/
Ratings & Reviews
- This app hasn’t received enough ratings or reviews to display an overview.
New pack: EARTH 365. 365 days of climate, land, oceans and the systems that connect them. Where do clouds come from, how are rocks made, why is the sea salty? Also part of the free first week.
The developer, kazunari aoki, indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy .
Data Not Collected
The developer does not collect any data from this app.
Accessibility
The developer has not yet indicated which accessibility features this app supports. Learn More
Information
- Seller
- kazunari aoki
- Size
- Up to 56.5 MB
- Category
- Education
- Compatibility
Requires iOS 26.4 or later.
- iPhone
Requires iOS 26.4 or later. - iPad
Requires iPadOS 26.4 or later. - Mac
Requires macOS 26.4 or later and a Mac with Apple M1 chip or later. - Apple Vision
Requires visionOS 26.4 or later.
- iPhone
- Languages
English and 9 more
- English, French, German, Italian, Japanese, Korean, Portuguese, Simplified Chinese, Spanish, Traditional Chinese
- Age Rating
4+
- 4+
- In-App Purchases
Yes
- SPACE 365 $5.99
- NATURE 365 $5.99
- SCIENCE 365 $5.99
- PSYCHOLOGY 365 $5.99
- HISTORY 365 $5.99
- EARTH 365 $5.99
- Copyright
- © 2026 Kazunari Aoki