Abstract
This paper introduces the Professional Noticing Journal (PNJ), a learner-centred artefact that keeps attention on students and enables professional noticing. Drawing on two lesson study teams, we show how PNJ entries anchored teaching decisions in student evidence and interpretations, surfaced recurring issues (tool use, units and language, and “answers without explanation”), and prompted targeted responses. Teams converged on portable routines—brief tool onboarding, visible anchors, just-in-time reviews, a Result–How–Meaning talk frame, and a non-tech route. The PNJ also served as a boundary object, coordinating roles and post-lesson discussions.