Naderman's progressive sonatas are designed to develop the technique of the intermediate pianist, with clear melodic lines and accessible harmonies. They are elegant and graceful, characteristic of the Classical period.
Focus on clean execution of Alberti bass figures and smooth melodic phrasing.
7 Sonates Progressives (Op.92) is rated Henle level 5 of 9 — late intermediate repertoire, roughly ABRSM grades 6–7.
You should be comfortable at Henle level 5 — meaning you can already play level 4–5 pieces cleanly. Learning it one level early is possible as a stretch piece, but more than that usually leads to months of frustration.
A typical performance of 7 Sonates Progressives (Op.92) lasts about 15 minutes.
7 Sonates Progressives (Op.92) is available as free public-domain sheet music on IMSLP — the score is linked directly from this page.