The movements of sonically-tagged Atlantic cod swimming within a large (80,000 mt) shoal of post-spawning ®sh on the northeast Newfoundland Shelf were related to the acoustically determined position of the shoal and event structure in the local ocean currents. For the ®rst several days of the study, a period when currents were unfavorable for shoreward transport, the tagged ®sh maintained station. There was little net movement of individual ®sh and no change in the geographical location of the shoal. Then, apparently in response to a shoreward current event, the cod moved with the¯ow. The tagged cod behaved as members of the shoal, in that their net movement was similar to that of the shoal itself. These observations further support the hypothesis that cod on the northeast Newfoundland Shelf selectively use currents for transport during their shoreward feeding migration. The cue to initiate migration by post-spawning cod is apparently an organized onshore¯ow exceeding a threshold velocity and duration. #

This study examined how facets of elementary teachers' pedagogical content knowledge are "engaged in practice" in the context of Problem-Based Learning (PBL). A secondary objective was to identify challenges teachers experienced during the development and implementation of PBL learning experiences. Collaborative Inquiry (Bray, Lee, Smith, & Yorks, 2000), a participatory, action-based inquiry approach was used as a means to develop and implement PBL. Outcomes report on how teachers developed and engaged various facets of their pedagogical content knowledge, including orientations to teaching science, and knowledge of and beliefs about curriculum, student learning, instruction, and assessment.Résumé: Cetteétude se penche sur la connaissance des contenus pédagogiques chez les enseignants du primaire, en particulier sur la façon dont cette connaissance est "centrée sur la pratique", dans le contexte de l'apprentissage par problèmes (APP). L'objectif secondaire de la recherche est de déterminer quels sont les défis que doivent relever les enseignants lorsqu'ils doivent mettre sur pied des projets d'apprentissage par problèmes.À cette fin, nous avons adopté la recherche collaborative proposée par Bray, Lee, Smith et Yorks (2000), un type de recherche participative fondée sur l'action. Les résultats montrent comment les enseignants ont mis en jeu différentes facettes de leur connaissance des contenus pédagogiques, y compris leurs orientations en enseignement des sciences et leurs connaissances sur les curriculums, l'apprentissage, l'enseignement et l'évaluation.