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Collaborative learning is an extensively used instructional technique by which individuals interact in small groups to learn to solve academic problems. This study aimed to determine the impact of task-specific prior knowledge on individual learners and collaborative groups that were instructed to collaborate. A 2 (individual vs. collaborative group) × 2 (novice vs. knowledgeable learners) factorial experiment with 228 students was carried out to examine the effects of these treatments on performance and mental effort in learning and its outcomes. As expected, knowledgeable individuals and knowledgeable collaborative groups outperformed novice individuals and novice collaborative groups in learning outcomes. Less knowledgeable, collaborating learners outperformed less knowledgeable, individual learners in learning outcomes. While more knowledgeable collaborating and individual learners performed equally well in the learning phase and the delayed test, on the retention test, collaborative groups demonstrated better performance. In general, collaboration benefited learning compared to individual learning in complex tasks, but performance depended on the learner task-specific prior knowledge. • Prior knowledge benefits collaborative and individual learning in complex tasks. • The effects of prior knowledge are more observable in learning outcomes. • Collaborative learning with advanced learners is redundant. [ABSTRACT FROM AUTHOR]

Abstract: In this work we provide evidence that granulocytes produce macrophage colony-stimulating factor (M-CSF) in the band cell stage and secrete it upon sodium caseinate-mediated differentiation to polymorphonuclear cells. We identified M-CSF in an enriched population of myeloid band cells from murine bone marrow using a chromophore-labeled monoclonal anti-M-CSF antibody. An ELISA assay was then used to detect secreted M-CSF in culture supernatants of enriched band cells differentiated to mature neutrophils using sodium caseinate. Colony formation in vitro by the supernatants from differentiating band cells was blocked by anti-M-CSF, thus suggesting that this factor is the only one responsible for this activity. Our data imply that casein can modulate hematopoiesis possibly via M-CSF production. Finally we discuss the possibility whether this M-CSF in concert with G-CSF could establish a cellular communication network between macrophages and granulocytes allowing them to simultaneously arrive at the inflammatory site. [Copyright &y& Elsevier]