8,790 research outputs found
Research-based assessment of students' beliefs about experimental physics: When is gender a factor?
The existence of gender differences in student performance on conceptual
assessments and their responses to attitudinal assessments has been repeatedly
demonstrated. This difference is often present in students' preinstruction
responses and persists in their postinstruction responses. However, one area in
which the presence of gender differences has not been extensively explored is
undergraduate laboratory courses. For example, one of the few laboratory
focused research-based assessments, the Colorado Learning Attitudes about
Science Survey for Experimental Physics (E-CLASS), has not been tested for the
existence of gender differences in students' responses. Here, we utilize a
national data set of responses to the E-CLASS to determine if they demonstrate
significant gender differences. We also investigate how these differences vary
along multiple student and course demographic slices, including course level
(first-year vs.\ beyond-first-year) and major (physics vs.\ non-physics). We
observe a gender gap in pre- and postinstruction E-CLASS scores in the
aggregate data both for the overall score and for most items individually.
However, for some subpopulations (e.g., beyond-first-year students) the size or
even existence of the gender gap depends on another dimension (e.g., student
major). We also find that for all groups the gap in postinstruction scores
vanishes or is greatly reduced when controlling for preinstruction scores,
course level, and student major.Comment: 11 pages, 3 figures, accepted to Phys. Rev. - PE
Students' views about the nature of experimental physics
The physics community explores and explains the physical world through a
blend of theoretical and experimental studies. The future of physics as a
discipline depends on training of students in both the theoretical and
experimental aspects of the field. However, while student learning within
lecture courses has been the subject of extensive research, lab courses remain
relatively under-studied. In particular, there is little, if any, data
available that addresses the effectiveness of physics lab courses at
encouraging students to recognize the nature and importance of experimental
physics within the discipline as a whole. To address this gap, we present the
first large-scale, national study ( and
) of undergraduate physics lab courses through analysis of
students' responses to a research-validated assessment designed to investigate
students' beliefs about the nature of experimental physics. We find that
students often enter and leave physics lab courses with ideas about
experimental physics as practiced in their courses that are inconsistent with
the views of practicing experimental physicists, and this trend holds at both
the introductory and upper-division levels. Despite this inconsistency, we find
that both introductory and upper-division students are able to accurately
predict the expert-like response even in cases where their views about
experimentation in their lab courses disagree. These finding have implications
for the recruitment, retention, and adequate preparation of students in
physics.Comment: 10 pages, 2 figures, Accepted to Phys. Rev. PE
Students' epistemologies about experimental physics: Validating the Colorado Learning Attitudes about Science Survey for Experimental Physics
Student learning in instructional physics labs represents a growing area of
research that includes investigations of students' beliefs and expectations
about the nature of experimental physics. To directly probe students'
epistemologies about experimental physics and support broader lab
transformation efforts at the University of Colorado Boulder (CU) and
elsewhere, we developed the Colorado Learning Attitudes about Science Survey
for Experimental Physics (E-CLASS). Previous work with this assessment has
included establishing the accuracy and clarity of the instrument through
student interviews and preliminary testing. Several years of data collection at
multiple institutions has resulted in a growing national data set of student
responses. Here, we report on results of the analysis of these data to
investigate the statistical validity and reliability of the E-CLASS as a
measure of students' epistemologies for a broad student population. We find
that the E-CLASS demonstrates an acceptable level of both validity and
reliability on measures of, item and test discrimination, test-retest
reliability, partial-sample reliability, internal consistency, concurrent
validity, and convergent validity. We also examine students' responses using
Principal Component Analysis and find that, as expected, the E-CLASS does not
exhibit strong factors.Comment: 10 pages, 4 figures, 7 tables, submitted to Phys. Rev. ST - PE
Upper-division student difficulties with Separation of Variables
Separation of variables can be a powerful technique for solving many of the
partial differential equations that arise in physics contexts. Upper-division
physics students encounter this technique in multiple topical areas including
electrostatics and quantum mechanics. To better understand the difficulties
students encounter when utilizing the separation of variables technique, we
examined students' responses to midterm exam questions and a standardized
conceptual assessment, and conducted think-aloud, problem-solving interviews.
Our analysis was guided by an analytical framework that focuses on how students
activate, construct, execute, and reflect on the separation of variables
technique when solving physics problems. Here we focus on student difficulties
with separation of variables as a technique to solve Laplace's equation in both
Cartesian and spherical coordinates in the context of junior-level
electrostatics. Challenges include: recognizing when separation of variables is
the appropriate tool; recalling/justifying the separated form of the potential
and the need for the infinite sum; identifying implicit boundary conditions;
and spontaneously reflecting on their solutions. Moreover, the type and
frequency of errors was often different for SoV problems in Cartesian and
spherical geometries. We also briefly discuss implication of these our findings
for instruction.Comment: 13 pages, 3 figures, submitted to Phys. Rev. ST-PE
Improvement or selection? A longitudinal analysis of students' views about experimental physics in their lab courses
Laboratory courses represent a unique and potentially important component of
the undergraduate physics curriculum, which can be designed to allow students
to authentically engage with the process of experimental physics. Among other
possible benefits, participation in these courses throughout the undergraduate
physics curriculum presents an opportunity to develop students' understanding
of the nature and importance of experimental physics within the discipline as a
whole. Here, we present and compare both a longitudinal and pseudo-longitudinal
analysis of students' responses to a research-based assessment targeting
students' views about experimental physics -- the Colorado Learning Attitudes
about Science Survey for Experimental Physics (E-CLASS) -- across multiple,
required lab courses at a single institution. We find that, while
pseudo-longitudinal averages showed increases in students' E-CLASS scores in
each consecutive course, analysis of longitudinal data indicates that this
increase was not driven by a cumulative impact of laboratory instruction.
Rather, the increase was driven by a selection effect in which students who
persisted into higher-level lab courses already had more expert-like beliefs,
attitudes, and expectations than their peers when they started the lower-level
courses.Comment: 6 pages, 1 figure, submitted as a short paper to Phys. Rev. PE
Multiple-choice Assessment for Upper-division Electricity and Magnetism
The Colorado Upper-division Electrostatics (CUE) diagnostic was designed as
an open-ended assessment in order to capture elements of student reasoning in
upper-division electrostatics. The diagnostic has been given for many semesters
at several universities resulting in an extensive database of CUE responses. To
increase the utility and scalability of the assessment, we used this database
along with research on students' difficulties to create a multiple-choice
version. The new version explores the viability of a novel test format where
students select multiple responses and can receive partial credit based on the
accuracy and consistency of their selections. This format was selected with the
goal of preserving insights afforded by the open-ended format while exploiting
the logistical advantages of a multiple-choice assessment. Here, we present
examples of the questions and scoring of the multiple-choice CUE as well as
initial analysis of the test's validity, item difficulty, discrimination, and
overall consistency with the open-ended version.Comment: 4 pages, 3 figures, accepted 2013 Physics Education Research
Conference proceeding
Validation and analysis of the coupled multiple response Colorado upper-division electrostatics (CUE) diagnostic
Standardized conceptual assessment represents a widely-used tool for
educational researchers interested in student learning within the standard
undergraduate physics curriculum. For example, these assessments are often used
to measure student learning across educational contexts and instructional
strategies. However, to support the large-scale implementation often required
for cross-institutional testing, it is necessary for these instruments to have
question formats that facilitate easy grading. Previously, we created a
multiple-response version of an existing, validated, upper-division
electrostatics diagnostic with the goal of increasing the instrument's
potential for large-scale implementation. Here, we report on the validity and
reliability of this new version as an independent instrument. These findings
establish the validity of the multiple-response version as measured by multiple
test statistics including item difficulty, item discrimination, and internal
consistency. Moreover, we demonstrate that the majority of student responses to
the new version are internally consistent even when they are incorrect, and
provide an example of how the new format can be used to gain insight into
student difficulties with specific content in electrostatics.Comment: 8 pages, 6 figures, submitted to Phys. Rev. ST-PE
Flight 1 technical report for experiment 74-36: Thermal migration of bubbles and their interaction with solidification interfaces
Specimens of gas saturated carbon tetrabromide were directionally solidified in a transparent furnace using a gradient freeze technique. The original temperature gradient was 5 C/cm and the cooling rate was 40 C/h. Progress of the experiment was monitored photographically. Gas bubbles were generated at the advancing solidification front in each of the three specimens. The gas bubbles were observed to increase in size, coalesce, and eventually be grown into the solid specimen under low gravity conditions. No bubble detachment from the interface was observed. Identical specimens processed in the laboratory showed bubble nucleation, bubble growth, and eventual bubble detachment due to buoyancy forces. Examination of the specimens showed a significantly greater void content in the low gravity processed samples. The grain size was observed to be finer in the low gravity processed samples
Analysis of selective chopper radiometer data
Data from SCR-B on Nimbus 5 have been processed to yield global, orbital temperatures at 10, 5, 2, 1, and 0.4 mb for the period January 1977 through April 1978 under the current task. In addition gridded values at 10 deg latitude by 20 deg longitude were prepared by space-time interpolation for the period January 1975 through April 1978. Temperature retrieval was based on regression of radiances against Meteorological Rocket Network data, with regressions recomputed at approximately six-month intervals. This data now completes a consistent time series from April 1970 to April 1978 for all available radiance data from SCR A and SCR B on Nimbus 4 and 5. The processing details for the current period are discussed, but is also applicable to the previous data periods. The accuracy of the temperature retrievals for each 6-month period for the entire eight years is given in the Appendices
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