Hide the results until the whole class has answered
A bar growing in front of thirty children recreates hands up exactly: the undecided watch the leader and join it. Collect first, reveal after, and the split you see is the one they actually held.
Write in the wrong answer you expect them to pick
The value of a check is in the distractors. If you cannot name the misconception you are hunting, the question will come back green and tell you nothing you can teach with.
One device between two is not a compromise
Pairs have to agree before they answer, which means the reasoning happens out loud in the room. Where phones are not allowed, a set of school laptops or tablets works the same way — the code is typed in, not scanned.
Two minutes of setup, or it will not happen on Tuesday
Build the questions once, put the code on the board and leave the room open through the lesson. Anything that needs a login per child, or an install, gets abandoned somewhere in week two.
Say out loud that nobody can see who answered what
Children check. Once they have worked out that the wrong answer costs them nothing in front of the class, the starter stops being a performance and starts being data.
Read the exit tickets before you plan the next lesson
They take four minutes to read for a class of thirty, and they are the only part of this that changes what you teach rather than what you know. Collecting them and not reading them is worse than not collecting them.