Thirteen randomly selected 9th-and lOth-grade students who studied an ecology unit -were interviewed, occasion, the students were presented with a handdrawn diagram of a food web and an aquarium. The food web contained a variety of fish, a fox, a rabbit, decomposing bacteria, heterotrophic and autotrophic protozoa, and terrestrial and aquatic plants. Arrows were drawn on the diagram indicating energy relations. The aquarium contained plants, snails, and fish. The

This study explored preservice teachers' (n = 25) knowledge structures and their mastery of content knowledge in relation to their ability to diagnose the strengths and weaknesses of a fourth grader's videotaped explanations of a scientific phenomenon, i.e., molecular kinetic properties of air. Participants' knowledge structures were analyzed using flow maps before and following a unit of instruction on molecular kinetic properties of air. Participants' diagnostic scores were obtained before and after instruction. An additional diagnostic score used to explore relationships between knowledge structures and participants' abilities to apply understandings in a novel task was obtained following instruction. Findings include a significant increase in the mean number of diagnostic scores following instruction (t = 5.6; p ≤ 0.00) and a positive correlation (r = 0.58; p ≤ 0.02) between knowledge structure complexity and participants' ability to diagnose the child's thinking on a novel molecular kinetics task. Implications for teacher education programs are discussed.

The abundance and diversity of gymnamoebae in three subsoils varying in compaction and water retention along a 1.2 m transect were documented as the local climatic conditions changed from late summer 1999 through mid-summer 2000. The mean density of gymnamoebae for the loose soil (1,655/g) was greater than either the most compact (1,468/g) or moderately compact soil (851/g). Minimum densities occurred in middle and late summer for all soils while significant (F = 38.803, < or = 0.0002) density peaks at 3.212/g occurred in early summer in the most compact soil, 2.928/g in the least compact, and 2,209/g in the moderately compact soil. Limax non-eruptive gymnamoebae (mt 2) correlated (r = 0.49, p < or = 0.016) with moisture while eruptive limax gymnamoebae ( 3) correlated with temperature (r = 0.07, p < or = 0.024), moisture (r = 0.58, p < or = 0.001) and precipitation (r = 0.46, p < or = 0.029). Flattened or discoid amoebae (mt 4) dominated throughout most of the survey, and the two limax groups showed inverse relationships. Chi-square analyses showed significant differences in the numbers of limax eruptive gymnamoebae compared to all other morphotypes on all but one sampling period.

No abstract

No abstract