Four measures, 4/4. Soprano is given. Click a lower staff; click again at another height to change its pitch. Enter selects a slot; ↑/↓ changes pitch, ←/→ moves between slots. Changing Quarter/Half resizes the selected slot without moving later notes; an uncovered beat becomes blank. Notes never cross a barline.

Major-key workbook: complete chord tones, with standard dominant-seventh and cadential tonic omissions. Inner voices may frustrate a leading tone down to the chord's fifth. Large-leap recovery and some doublings are suggestions. Sandbox figures show intervals above the actual bass; “—” means incomplete or no bass, “?” means a voice lies below it. Reset clears your three lower voices. Refresh starts a fresh workbook.