The Effect of Broadleaf Canopies on Survey-grade Horizontal GPS/GLONASS Measurements

A study was conducted to empirically determine the degradation of survey-grade GPS horizontal position measurements due to the effects of broadleaf forest canopies. The measurements were taken using GPS/GLONASS-capable receivers measuring C/A and P-codes, and carrier phase. Fourteen survey markers were chosen in central Connecticut to serve as reference markers for the study. These markers had varying degrees of sky obstruction due to overhanging tree canopies. Sky obstruction was measured by photographing the sky with a 35mm reflex camera fitted with a hemispherical lens. The negative was scanned and the image mapped using an equal- area projection to remove the distortion caused by the lens. The resulting digital image was thresholded to produce a black-and-white image in which a count of the black pixels is a measure of sky-area obstruction. The locations of the markers were determined independently before the study. During the study, each marker was occupied for four 20-minute sessions over the period of one week in mid-July, 1999. The location of the study markers produced relatively long baselines, as compared with similar studies. We compared the accuracy of GPS-only vs. GPS&GLONASS as a function of sky obstruction. Based on our results, GLONASS observations did not improve or degrade the accuracy of the position measurements. There is a loss of 2mm of accuracy per percent of sky obstruction for both GPS only and GPS&GLONASS.

The Effect of Direct Instruction versus Discovery Learning on the Understanding of Science Lessons by Second Grade Students

This study examined the effectiveness of discovery learning and direct instruction in a diverse second grade classroom. An assessment test and transfer task were given to students to examine which method of instruction enabled the students to grasp the content of a science lesson to a greater extent. Results demonstrated that students in the direct instruction group scored higher on the assessment test and completed the transfer task at a faster pace; however, this was not statistically significant. Results also suggest that a mixture of instructional styles would serve to effectively disseminate information, as well as motivate students to learn.

The Relationship of Student Demographics to 10th Grade MCAS Test Anxiety

The intensification of consequential testing situations is associated with an increase in anxiety among American students (Casbarro, 2005). Test anxiety can have negative effects on student test performance (Everson, Millsap, & Rodriguez, 1991). If test anxiety has the potential to decrease students’ test scores, it becomes a factor that can threaten the validity of any inferences drawn between test scores and student progress (Cizek & Burg, 2006). There are several factors that relate closely to test anxiety (Cizek & Burg, 2006). Variables of key influence include gender, socioeconomic status, and teacher-manifested anxiety (Hembree, 1988). Another influence upon test anxiety is students’ participation in academic support programs to prepare them for exit examinations. The purpose of this study was to examine the relationship between 10th grade high school student gender, socioeconomic status, perceived teacher anxiety, and student preparedness with levels of the Massachusetts Comprehensive Assessment System (MCAS) test anxiety. It appears that few studies have examined levels of high school test anxiety in regards to this specific high-stakes MCAS exit exam required for high school graduation. A two-phase sequential mixed-methods research design was used to survey (N=156) 10th grade students represented by a sampling of (n=80) students with low socioeconomic status and (n=76) students with high socioeconomic status regarding their levels of test anxiety in relation to upcoming MCAS testing. A multiple regression analysis was used to measure the relationship between the predictor variables (gender, socioeconomic status, perceived teacher anxiety, and student preparedness) with the criterion variable of student test anxiety using the Test Anxiety Inventory (TAI). Personal interviews with (n=20) volunteer students provided rich explanations of students’ academic self-efficacy, their perceptions of their performance on the upcoming MCAS exam, and their use of strategies to reduce their levels of test anxiety. Personal interviews with (n=12) volunteer school administrators and teachers provided descriptions of their perceptions of how test anxiety affected their students’ performance. A major quantitative finding of this study was that the variables of student socioeconomic status and student ratings of teacher anxiety accounted for the variance in students’ levels of surveyed test anxiety (R2 = .06, p = .033, small to medium effect size). These results indicate that different student populations vary in their readiness skills to successfully participate in consequential testing situations. Consequently, high-test anxious students would require emotional preparation as well as academic preparation when confronting high-stakes testing. The results have the potential to re-shape the format of schools’ MCAS test preparation efforts.