Study
Two sections. The first teaches the shape of a beat and what the leads are; the second is the rhythm library to practise on. Neither is marked or timed.
Section 1 · Start here
ECG basics
What a lead actually measures and why there are twelve of them from ten electrodes. The P wave, QRS, ST segment and T wave with their normal values, marked on a real complex. Which leads look at which wall, and the artery that feeds it.
Section 2 · Reference
ECG rhythm library
Twenty-five rhythms drawn by the calibrated engine on true mm/mV paper, with ectopy, ST elevation, live measurements, a quiz and a printable report. Measure them against the grid the way you would a real strip.