How the camera reads the cards

While a question is open, your phone looks for answer cards in the camera picture. Every card in view is read at once, so you can sweep the room slowly instead of pointing at each student. Here’s what it does, and why.

It reads each card three times

An answer counts only after the phone sees the same letter on the same card three times. A student who is still turning their card, or a card caught at an odd angle for a moment, doesn’t get a wrong answer recorded. Three reads take about a second while the card is in view.

If a student changes their mind and turns the card to another letter, the phone starts counting again, and the new letter replaces the old one once it’s been seen three times.

It never guesses

A card held at an angle, halfway between two letters, isn’t read at all. Turning it straight is enough. The phone also leaves out cards it can’t trust and tells you about them below the picture:

Unrecognised cards: a card that isn’t in this class, such as one printed for another class.

Cards seen twice: the same card twice in one picture, usually a photocopy. Neither copy is recorded.

A letter the question doesn’t have: a D on a question with three options. It’s shown, not recorded.

A paused or frozen picture is never read either, so one question’s picture can’t be counted against the next.

It saves your battery

A lesson can run for an hour on the same phone, so the camera only works as hard as it needs to:

It reads about four pictures a second, which is plenty for a card held still, and asks the camera for half the pictures it would usually send.

It stops reading whenever there’s nothing to read: between questions, once everyone’s answer is in and the camera folds away, when you tap Hide camera, and when the phone is held sideways.

The camera turns off while the explanation shows, and at the end of the lesson. It stays on while the class looks at the answer counts, so it’s ready the moment the next question opens.

Tap instead turns the camera off completely.

It sees across the room

The phone uses its camera’s sharpest picture, so a Classroom card reads from up to about 4 m away and a Large room card from up to about 7 m. Full screen shows the whole picture the phone is reading, edge to edge.

It pauses when the picture is sideways

A sideways picture would turn every letter by a quarter, so a card showing A would read as B. When your phone can tell it’s held sideways, it pauses and says so until you turn it back.

It tells you when it’s paused

Sometimes a phone stops sending the camera picture, for example after the screen locks or you leave full screen. Your phone says Scanning paused over the picture, with the reason. It restarts the picture by itself first, and asks you to tap Restart camera only if it can’t.

The video stays on your phone

The cards are read on your phone. The video is never sent or saved: only each student’s letter goes to the lesson.

Answers aren’t lost when the connection drops

If your phone loses its connection, the answers it reads are kept on the phone and sent as soon as it reconnects. An answer that arrives after its question has closed isn’t counted, so a late read can’t change a result the class has already seen.