Play middle C on every beat. One hand, one key.
Why this matters: rhythm without notes is the cheap way to drill timing. By landing on one note, you isolate the timing layer — no decisions about which key, just when. Later, the rhythm transfers to actual phrases.
8 trials at 80 bpm. 8 beats per trial. The click marks every beat — tap C4 in time. Other keys count as misses. Hit 6/8 per trial.