Effectiveness of student response systems in terms of learning environment, attitudes and achievement

In order to investigate the effectiveness of using Student Response Systems (SRS) among grade 7 and 8 science students in New York, the How Do You Feel About This Class? (HDYFATC) questionnaire was administered to 1097 students (532 students did use SRS and 565 students who did not use SRS). Data analyses attested to the sound factorial validity and internal consistency reliability of the HDYFATC, as well as its ability to differentiate between the perceptions of students in different classrooms. Very large differences between users and non-users of SRS, ranging from 1.17 to 2.45 standard deviations for various learning environment scales, attitudes and achievement, supported the efficacy of using SRS

Effects of two oil dispersants on phototaxis and swimming behaviour of barnacle larvae

The effects of two oil dispersants (Vecom B-1425 GL and Norchem OSD-570) mixed with diesel oil on the survival and behaviour of the stage II nauplii of the barnacle Balanus amphitrite were investigated. The 24 and 48-hour LC50 values for Vecom B-1425 GL:diesel mixture were 514 and 48 mg 1-1 respectively, while respective values for Norchem OSD-570:diesel mixture were 505 and 71 mg 1-1. Under sublethal concentrations, increased levels of the dispersant:diesel mixtures caused a reduction in phototactic responses. Balanus amphitrite nauplii failed to exhibit phototactic responses when exposed to Vecom B-1425 GL:diesel mixtures of 400 mg 1-1 and higher for 24 hours. A longer exposure time of 48 hours further reduced the Lowest Observable Effect Concentrations (LOECs) to 60 mg 1-1. The LOECs for Norchem OSD-570:diesel mixtures under exposure periods of 24 and 48 hours were 400 and 80 mg 1-1 respectively. The curvilinear velocities (VCL) and straight-line velocities (VSL) of the stage II nauplii ranged from 0.7-1.1 and 0.2-0.4 mm s-1 respectively. Increased concentrations of dispersant:diesel mixtures caused a significant change in the curvilinear and straight-line velocities. Both oil dispersants, dispersant:diesel mixtures of 20 to 40 mg 1-1 caused significant increases in VCL, but no significant change in VSL. Dispersant:diesel mixtures of 100 mg 1-1 and higher resulted in a reduction in VSL for both dispersants. ©1997 Kluwer Academic Publishers.link_to_subscribed_fulltex