A Trial List of Objectives of Experimental Work in Science Education

Summaries

English

Teaching science nowadays includes more teaching of experimental methods than it formerly did, and this trend may well continue. Teaching experimental methods means teaching how to solve problems in an experimental way, which is quite different from teaching the laws and facts of science. The need for a list of practical objectives has existed in the past and will be felt, more and more, in the future. An attempt to construct new lists for the three sciences was made by staff members of CITO, the Dutch Institute for Educational Measurement, specially, though not only, for the purpose of assessment. Intended characteristics of the lists are exhaustiveness; restriction to cognitive and psycho‐motor skills and abilities; formulation in terms of observable pupil behaviour; specification up to four levels; and identity for physics and chemistry up to three levels.     

The impact of technology and a no remediation policy on non-traditional students

A Hunter College librarian, with public library experience, offered a series of drop-in workshops Saturday afternoons open to all students and questions regarding Web or Windows use in the academic year, 2000-2001. The intention of the workshops was to address the continuous needs of students lacking technological and informational literacy. The success of these workshops led to this investigation of the implications of 21st century technology on non-traditional students from the perspective of bibliographic instruction as well as reference desk service. The perspective is that of the urban educational environment of City University of New York and Hunter College. The histories of open admissions at CUNY and the current efforts to abolish remediation are examined.     

A pipelined architecture for distributed text query evaluation

Two principal query-evaluation methodologies have been described for cluster-based implementation of distributed information retrieval systems: document partitioning and term partitioning. In a document-partitioned system, each of the processors hosts a subset of the documents in the collection, and executes every query against its local sub-collection. In a term-partitioned system, each of the processors hosts a subset of the inverted lists that make up the index of the collection, and serves them to a central machine as they are required for query evaluation. In this paper we introduce a pipelined query-evaluation methodology, based on a term-partitioned index, in which partially evaluated queries are passed amongst the set of processors that host the query terms. This arrangement retains the disk read benefits of term partitioning, but more effectively shares the computational load. We compare the three methodologies experimentally, and show that term distribution is inefficient and scales poorly. The new pipelined approach offers efficient memory utilization and efficient use of disk accesses, but suffers from problems with load balancing between nodes. Until these problems are resolved, document partitioning remains the preferred method. Alistair Moffat was supported by the Australian Research Council, the ARC Special Research Center for Perceptive and Intelligent Machines in Complex Environments, and the NICTA Victoria Laboratory. William Webber and Justin Zobel were supported by the Australian Research Council. Ricardo Baeza-Yates was supported by Grant P01-029-F from Millennium Initiative of Mideplan, Chile; and by the University of Melbourne as a visiting scholar at the time this project was undertaken.