Luke tells Theophilus why he wrote his Gospel: “that you may have certainty concerning the things you have been taught” (Luke 1:4, ESV). The verb behind “taught” is κατηχέω, to instruct by word of mouth. It is where the church gets “catechize.” It names an old method: one person asks, the other answers, and the asking is repeated until the answer is known by heart.
I am a seminarian with Greek vocabulary to learn and a catechism to memorize, and I own the same devices as everyone else. I did not need more study materials. I needed something that would ask me the question whether or not I felt like being asked. So I built it, and named it after the verb.
On the Mac
Katecheo for Mac sits in the menu bar. Every so often it locks the screen with one flashcard and keeps it locked until the card is answered. A right answer earns a longer wait before the next question, from ten minutes up to a full hour. A wrong answer shortens it.
The question waits until I have stopped typing, and it holds off during a call or anything running full screen, and by default during a video. There is a way out of a lock, which is to hold Escape for five seconds, and using it is written into the weekly report.
It also keeps a schedule. A block of work and rest goes on the calendar, and when it begins, only the apps and sites I allowed for that block stay open. A session I skip is counted against me in the weekly report, by the minutes missed.
The Mac app will take any deck that has right answers. Two sets come with it, New Testament Greek vocabulary and the Westminster Shorter Catechism, and a built-in DeckBuilder helps turn a set of notes into a deck of your own: it writes the prompt for an AI assistant and checks the file that comes back.
On the iPhone
The phone is the harder device, so the iPhone app works the other way around. It counts the minutes I spend on the phone. When they run out, it covers my other apps until I answer one question. Phone and FaceTime are never covered, and I choose which apps always stay open.
Three decks are built in: 646 words of Greek vocabulary, all 107 questions of the Shorter Catechism, and 500 key passages in the ESV, where the verse is shown and the reference has to be found. Study sessions can be scheduled with an alarm, with quiet time to cover distracting apps until the session ends.
What It Costs
Nothing. Both apps are free, with no account, no server, and no analytics. What I study stays on the device I studied it on.
The Mac app can be downloaded today, for macOS 15 or later. The same page will carry the iPhone app’s App Store link once Apple approves it.
Moses told Israel what to do with the words of God: “You shall teach them diligently to your children, and shall talk of them when you sit in your house, and when you walk by the way, and when you lie down, and when you rise” (Deuteronomy 6:7, ESV). That command was given to fathers about their children, and no app can keep it for anyone. But the picture in it is of words that keep coming up through an ordinary day, and that picture is what I had in mind. Katecheo is a small machine for making the question come up again.