teacher is teaching both chemistry and physics, requiring more preparation time (American Association of Physics Teachers, 2002). The guidelines note that simply maintaining the laboratory requires at least one class period per day, and, if schools will not provide teachers with that time, they suggest that those schools either employ laboratory technicians or obtain student help.

The National Science Teachers Association takes a slightly different position, suggesting that administrators provide teachers with a competent paraprofessional. The paraprofessional would help with setup, cleanup, community contacts, searching for resources, and other types of support (National Science Teachers Association, 1990).

No national survey data are available to indicate whether science teachers receive adequate preparation time or assistance from trained laboratory technicians. Some individual teachers told our committee that they did not have adequate preparation and cleanup time.

Finally, adequate time is essential for student learning in laboratory experiences. On the basis of a review of the available research, Lunetta (1998, p. 253) suggests that, for students, “time should be provided for engaging students in driving questions, for team planning, for feedback about the nature and meaning of data, and for discussion of the implications of findings,” and laboratory journals “should provide opportunities for individual students to reflect upon and clarify their own observations, hypotheses, conceptions.”

School administrators can take several approaches to providing time for this type of ongoing discussion and reflection that supports student learning during laboratory experiences. Block scheduling is one approach schools have used to provide longer periods of time for laboratory activities and discussion. In this approach classes meet every other day for longer blocks of about 90-100 minutes, instead of every day for 40 or 45 minutes. However, an analysis of national survey data indicates that teachers in block schedules do not incorporate more laboratory experiences into their instruction (Smith, 2004). In addition, there is little research on whether use of block scheduling influences teachers’ instruction or enhances student learning.

In another approach, schools can schedule science classes for double periods to allow more time for both carrying out investigations and reflecting on the meaning of those investigations. In an ideal world, administrators would provide adequate laboratory space and time to allow students to continue investigations over several weeks or months, and they would also provide time for students to work outside regular school hours. One study found that, when laboratories were easily accessible, 14- and 15-year-old students who used the facilities during their free time reported increased interest in academics and took advanced science courses (Henderson and Mapp, 2002).



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