Tap along while the click plays, then keep that exact tempo from your inner clock after it goes silent.
A click plays the target tempo for a few bars with a pulsing disc; tap along on each beat to lock in. Then the click cuts out and the canvas dims, you must keep tapping the identical tempo from memory. At the end your drift is measured against the target.
Tempo Lock trains the internal clock that lets musicians hold a steady tempo without a metronome.
Tapping along to a click and then continuing after it stops is internal tempo — the ability to hold a pulse without a reference.
Cutting the click and dimming the canvas is the original test.
Keeping time with a metronome is a following task and keeping it without one is a generating task, and they are not the same ability. Ensembles fall apart in exactly this gap, which is why the drill is standard and why most people drift in a consistent personal direction.
Further reading: After the Click Cuts Out
Tempo Lock trains the internal clock that lets musicians hold a steady tempo without a metronome. It is an original, free browser game built in-house for PlayPendium.
The game begins with a click that marks the tempo, then that click falls silent, and the player must keep tapping the same tempo through the silent bars.