The impact of the MARS curriculum on students' ability to coordinate theory and evidence

The Model-Assisted Reasoning in Science (MARS) project seeks to promote model-centered instruction as a means of improving middle-school science education. As part of the evaluation of the sixth-grade curriculum, performance of MARS and non-MARS students was compared on a curriculum-neutral task. Fourteen students participated in structured interviews in which they experimented with a balance apparatus that provided three manipulable variables (two affected balance, one was a non-causal distractor variable). Although both groups were equally able to identify and test variables, all MARS students discovered a quantitative rule to describe the operation of the balance, whereas only one non-MARS student did so. MARS students discovered this numerical relationship through experimentation, regardless of their scientific reasoning profile (i.e. theory-generating, theory-modifying, or theory-preserving). The critical components of MARS instruction that may foster the ability to flexibly coordinate theory and evidence include multiple opportunities to draw conclusions from data and an emphasis on the successive refinement of models.     

A Note on Non-parallelism of Pretest and Posttest Measures in Assessing Change

In the study of differences, change, or growth, pretest and posttest measures often cannot be considered to be “parallel” in the usual test-theory sense. Empirical data supporting this conclusion is presented. But under this condition of non-parallelism of pretest and posttest measures, it is possible for change scores to be more reliable and more valid than ordinarily believed by most psychometricians.     

On the perennial argument about grading “on the curve” in college courses

If letter grades assigned in a course are determined by the percent of objective test items answered correctly, then under various assumptions about the mean and standard deviation of normally distributed test scores, the distribution of the percent of students receiving each letter grade is highly anomalous. Conversely, if one insists that letter grades be “reasonably” distributed and at the same time determined by a typical percentage scheme, then allowed test parameters are severely constrained and not the ones which psychometricians consider most defensible. One recourse available to an instructor who does not wish to grade “on the curve” is to adjust the test parameters to dubious values by manipulation of item difficulty so that a desired grade distribution based on percentages is achieved. This informal adjustment procedure constitutes an indirect and inefficient method of employing test norms — in effect, grading “on the curve.”     

Achieving extra‐genre rhetorical goals: Disarming expectations

This study employed turning point analysis to examine developing mentor relationships and the association between mentor relationships and individual‐organizational relationships. Graduate students from three communication departments reported turning points which they experienced during the early development of their mentor relationships. Findings indicated that many turning points occurred of which have previously been assumed to occur in later stages of relationship development. Some types of turning points were associated with greater changes in identification with the mentors. Others were associated with greater changes in identification with the departments. Results call broad phase models of mentor relational development into question. Secondly, results indicate that mentor relationships are not necessarily associated with individual‐organizational relationships. Mentor relationships, then, should not be assumed to benefit organizations.     

The Short-Term Effects of a Computer-Based Pregnancy,STD, and HIV Prevention Program

A computer- and Internet-based intervention was designed to influence several variables related to the prevention of pregnancy, STDs, and HIV in rural adolescents. Three-hundred and thirty-eight tenth-graders enrolled in two rural public high schools participated in this field experiment. Results indicate that students in the experimental school had greater knowledge, greater condom negotiation efficacy, greater situational efficacy, and more favorable attitudes toward waiting to have sex than students in the control school. In tandem, the results suggest that computer-based programs may be a cost-effective and easily replicable means of providing teens with basic information and skills necessary to prevent pregnancy, STDs, and HIV.     

Understanding How Families Use Magnifiers During Nature Center Walks

This analysis uses a sociocultural learning theory and parent–child interaction framework to understand families’ interactions with one type of scientific tool, the magnifier, during nature walks offered by a nature center. Families were video recorded to observe how they organized their activities where they used magnifiers to explore in the outdoors. Findings include that families used magnifiers for scientific inquiry as well as for playful exploration. Using the concept of guided facilitation where families develop roles to support their joint endeavor, three roles to support family thinking were found to be: (a) tool suggester, (b) teacher, and (c) exploration ender. Some families struggled to use magnifiers and often, parents and older siblings provided support for younger children in using magnifying lenses. Implications to informal science learning theory are drawn and suggestions for future family learning research are offered: (a) inclusion of sociocultural and situated perspectives as theories to study informal learning in outdoor spaces, (b) further study on the role of siblings in family interactions, (c) design-based research is needed to encourage family role-taking when engaging in science practices, and (d) new conceptualizations on how to design informal programs that support science learning while leaving space for visitors’ personal agendas and interests that can guide the families’ activities.     

The Reliability of Difference Scores in Populations and Samples

This study was an investigation of the relation between the reliability of difference scores, considered as a parameter characterizing a population of examinees, and the reliability estimates obtained from random samples from the population. The parameters in familiar equations for the reliability of difference scores were redefined in such a way that determinants of reliability in both populations and samples become more transparent. Computer simulation was used to find sample values and to plot frequency distributions of various correlations and variance ratios relevant to the reliability of differences. The shape of frequency distributions resulting from the simulations and the means and standard deviations of these distributions reveal the extent to which reliability estimates based on sample data can be expected to meaningfully represent population reliability.     

An examination of the use of audiovisual media in reducing prejudice

This study was designed to evaluate the effectiveness of audiovisual media as an instructional technique for altering ethnic attitudes among young children. Subjects were 153 children between the ages of five and nine, randomly assigned to one of three groups: Group 1 (Control), Group 2 (subjects viewed one film) or Group 3 (subjects viewed two films). The findings indicated that Group 2 and Group 3 gave significantly fewer prejudiced responses than Group 1 (p < .01). Furthermore, demographic variables (i.e., age, sex, or ethnicity of subject and tester) did not affect the ability of the treatment to modify attitudes. Both the implications and the limitations of these findings are discussed.