The relationship of attitudes toward science, cognitive style, and self-concept to achievement in chemistry at the secondary school level

There is currently a crisis in science education in the United States. This statement is based on the National Science Foundation's report stating that the nation's students, on average, still rank near the bottom in science and math achievement internationally. ^ This crisis is the background of the problem for this study. This investigation studied learner variables that were thought to play a role in teaching chemistry at the secondary school level, and related them to achievement in the chemistry classroom. Among these, cognitive style (field dependence/independence), attitudes toward science, and self-concept had been given considerable attention by researchers in recent years. These variables were related to different competencies that could be used to measure the various types of achievement in the chemistry classroom at the secondary school level. These different competencies were called academic, laboratory, and problem solving achievement. Each of these chemistry achievement components may be related to a different set of learner variables, and the main purpose of this study was to investigate the nature of these relationships. ^ Three instruments to determine attitudes toward science, cognitive style, and self-concept were used for data collection. Teacher grades were used to determine chemistry achievement for each student. ^ Research questions were analyzed using Pearson Product Moment Correlation Coefficients and t-tests. Results indicated that field independence was significantly correlated with problem solving, academic, and laboratory achievement. Educational researchers should therefore investigate how to teach students to be more field independent so they can achieve at higher levels in chemistry. ^ It was also true that better attitudes toward the social benefits and problems that accompany scientific progress were significantly correlated with higher achievement on all three academic measures in chemistry. This suggests that educational researchers should investigate how students might be guided to manifest more favorable attitudes toward science so they will achieve at higher levels in chemistry. ^ An overall theme that emerged from this study was that findings refuted the idea that female students believed that science was for males only and was an inappropriate and unfeminine activity. This was true because when the means of males and females were compared on the three measures of chemistry achievement, there was no statistically significant difference between them on problem solving or academic achievement. However, females were significantly better in laboratory achievement. ^

Cascading ecological effects of low-level phosphorus enrichment in the Florida Everglades

Few studies have examined long-term ecological effects of sustained low-level nutrient enhancement on wetland biota. To determine sustained effects of phosphorus (P) addition on Everglades marshes we added P at low levels (5, 15, and 30 µg L-1 above ambient) for 5 yr to triplicate 100-m flow-through channels in pristine marsh. A cascade of ecological responses occurred in similar sequence among treatments. Although the rate of change increased with dosing level, treatments converged to similar enriched endpoints, characterized most notably by a doubling of plant biomass and elimination of native, calcareous periphyton mats. The full sequence of biological changes occurred without an increase in water total P concentration, which remained near ambient levels until Year 5. This study indicates that Everglades marshes have a near-zero assimilative capacity for P without a state change, that ecosystem responses to enrichment accumulate over time, and that downstream P transport mainly occurs through biota rather than the water column.

Improved Annual Average Daily Traffic (AADT) estimation for local roads using parcel-level travel demand modeling

Annual Average Daily Traffic (AADT) is a critical input to many transportation analyses. By definition, AADT is the average 24-hour volume at a highway location over a full year. Traditionally, AADT is estimated using a mix of permanent and temporary traffic counts. Because field collection of traffic counts is expensive, it is usually done for only the major roads, thus leaving most of the local roads without any AADT information. However, AADTs are needed for local roads for many applications. For example, AADTs are used by state Departments of Transportation (DOTs) to calculate the crash rates of all local roads in order to identify the top five percent of hazardous locations for annual reporting to the U.S. DOT. ^ This dissertation develops a new method for estimating AADTs for local roads using travel demand modeling. A major component of the new method involves a parcel-level trip generation model that estimates the trips generated by each parcel. The model uses the tax parcel data together with the trip generation rates and equations provided by the ITE Trip Generation Report. The generated trips are then distributed to existing traffic count sites using a parcel-level trip distribution gravity model. The all-or-nothing assignment method is then used to assign the trips onto the roadway network to estimate the final AADTs. The entire process was implemented in the Cube demand modeling system with extensive spatial data processing using ArcGIS. ^ To evaluate the performance of the new method, data from several study areas in Broward County in Florida were used. The estimated AADTs were compared with those from two existing methods using actual traffic counts as the ground truths. The results show that the new method performs better than both existing methods. One limitation with the new method is that it relies on Cube which limits the number of zones to 32,000. Accordingly, a study area exceeding this limit must be partitioned into smaller areas. Because AADT estimates for roads near the boundary areas were found to be less accurate, further research could examine the best way to partition a study area to minimize the impact.^