arXiv subjects

H. J. Lewandowski

Publications and source records attributed to H. J. Lewandowski.

At least 55 records · Page 3Linked to original sources

arXiv2020

Student perceptions of laboratory classroom activities and experimental physics practice

We report results from a study designed to identify links between undergraduate students' views about experimental physics and their engagement in multiweek projects in lab courses. Using surveys and interviews, we explored whether students perceived particular classroom activities to be features of experimental physics practice. We focused on 18 activities, including maintaining lab notebooks, fabricating parts, and asking others for help. Interviewees identified activities related to project execution as intrinsic to experimental physics practice based on high prevalence of those activities in interviewees' own projects. Fabrication-oriented activities were identified as conditional features of experimentation based on differences between projects, which interviewees attributed to variations in project resources. Interpersonal activities were also viewed as conditional features of experimentation, dependent upon one's status as novice or expert. Our findings suggest that students' views about experimental physics are shaped by firsthand experiences of their own projects and secondhand experiences of those of others.

physics.ed-ph↗

arXiv2020

Impact of a course transformation on students' reasoning about measurement uncertainty

Physics lab courses are integral parts of an undergraduate physics education, and offer a variety of opportunities for learning. Many of these opportunities center around a common learning goal in introductory physics lab courses: measurement uncertainty. Accordingly, when the stand-alone introductory lab course at the University of Colorado Boulder (CU) was recently transformed, measurement uncertainty was the focus of a learning goal of that transformation. The Physics Measurement Questionnaire (PMQ), a research-based assessment of student understanding around statistical measurement uncertainty, was used to measure the effectiveness of that transformation. Here, we analyze student responses to the PMQ at the beginning and end of the CU course. We also compare such responses from two semesters: one before and one after the transformation. We present evidence that students in both semesters shifted their reasoning in ways aligned with the measurement uncertainty learning goal. Furthermore, we show that more students in the transformed semester shifted in ways aligned with the learning goal, and that those students tended to communicate their reasoning with greater sophistication than students in the original course. These findings provide evidence that even a traditional lab course can support valuable learning, and that transforming such a course to align with well-defined learning goals can result in even more effective learning experiences.

physics.ed-ph↗

arXiv2020

Teaching labs during a pandemic: Lessons from Spring 2020 and an outlook for the future

We report results from a survey of lab instructors on how they adapted their courses in the transition to emergency remote teaching due to the COVID-19 pandemic. The purpose of this report is to share the experiences of instructors in order to prepare for future remote teaching of labs. We include summaries of responses to help illustrate the types of lab activities that were done, learning goals for the remote labs, motivations for instructors' choices, challenges instructors faced, and ways in which instructors and students communicated. This is a first step in a larger project as part of an NSF RAPID grant to understand what happened during the switch to remote labs and how it impacted teaching methods and student learning.

physics.ed-ph↗

arXiv2020

Framework of goals for writing in physics lab classes

Writing is an integral part of the process of science. In the undergraduate physics curriculum, the most common place that students engage with scientific writing is in lab classes, typically through lab notebooks, reports, and proposals. There has not been much research on why and how we include writing in physics lab classes, and instructors may incorporate writing for a variety of reasons. Through a broader study of multiweek projects in advanced lab classes, we have developed a framework for thinking about and understanding the role of writing in lab classes. This framework defines and describes the breadth of goals for incorporating writing in lab classes, and is a tool we can use to begin to understand why, and subsequently how, we teach scientific writing in physics.

physics.ed-ph↗

arXiv2020

Collisions Between Ultracold Atoms and Cold Molecules in a Dual Electrostatic-Magnetic Trap

Measurements of interactions between cold molecules and ultracold atoms can allow for a detailed understanding of fundamental collision processes. These measurements can be done using various experimental geometries including where both species are in a beam, where one species is trapped, or when both species are trapped. Simultaneous trapping offers significantly longer interaction times and an associated increased sensitivity to rare collision events. However, there are significant practical challenges associated with combining atom and molecule systems, which often have competing experimental requirements. Here, we describe in detail an experimental system that allows for studies of cold collisions between ultracold atoms and cold molecules in a dual trap, where the atoms and molecules are trapped using static magnetic and electric fields, respectively. As a demonstration of the system's capabilities, we study cold collisions between ammonia ($^{14}$ND$_{3}$ and $^{15}$ND$_{3}$) molecules and rubidium ($^{87}$Rb and $^{85}$Rb) atoms.

physics.atom-ph↗

arXiv2019

Using the Life Grid Interview Technique in Science Education Research

Background: Qualitative interviewing is a common tool that has been utilized by Science, Technology, Engineering, and Mathematics (STEM) education researchers to explore and describe the experiences of students, educators, or other educational stakeholders. Some interviewing techniques use co-creation of an artifact, such as a personal timeline, as a unique way to elicit a detailed narrative from a respondent. The purpose of this commentary is to describe an interview artifact called a life grid. First used and validated in medical sociology to conduct life course research, we adapted the life grid for use in research on undergraduate STEM education. We applied the life grid interview technique to two contexts: 1) students in an advance degree program reflecting on their entire undergraduate career as a biology major, and 2) students in an undergraduate physics program reflecting on a multi-week lab project. Results: We found that the life grid supported four important attributes of an interview: facilitation of the respondents' agency, establishment of rapport between interviewers and respondents, enhanced depth of the respondents' narratives, and the construction of more accurate accounts of events. We situate our experiences with respect to those attributes and compare them with the experiences detailed in literature. Conclusions: We conclude with recommendations for future use of the life grid technique in undergraduate STEM education research. Overall, we find the life grid to be a valuable tool to use when conducting interviews about phenomena with a chronological component.

physics.ed-ph↗

arXiv2019

Preliminary model for student ownership of projects

In many upper-division lab courses, instructors implement multiweek student-led projects. During such projects, students may design and carry out experiments, collect and analyze data, document and report their findings, and collaborate closely with peers and mentors. To better understand cognitive, social, and affective aspects of projects, we conducted an exploratory investigation of student ownership of projects. Ownership is a complex construct that refers to, e.g., students' willingness and ability to make strategic decisions about their project. Using data collected through surveys and interviews with students and instructors at five institutions, we developed a preliminary model for student ownership of projects. Our model describes student interactions with the project during three phases: choice of topic, execution of experiment, and synthesis of results. Herein, we explicate our model and demonstrate that it maps well onto students' and instructors' conceptions of ownership and ideas presented in prior literature.

physics.ed-ph↗

arXiv2019

Quantum-State-Specific Reaction Rate Measurements for the Photo-induced Reaction Ca$^+$ + O$_2$ $\rightarrow$ CaO$^+$ + O

Atoms and molecules often react at different rates depending on their internal quantum states. Thus, controlling which internal states are populated can be used to manipulate the reactivity and can lead to a more detailed understanding of reaction mechanisms. We demonstrate this control of reactions by studying the excited state reaction reaction Ca$^+$ + O$_2$ $\rightarrow$ CaO$^+$ + O. This reaction is exothermic only if Ca$^+$ is in one of its excited electronic states. Using laser-cooling and electrodynamic trapping, we cool and trap Ca$^+$ at millikevin temperatures for several minutes. We can then change the fraction of time they spend in each of the two excited states by adjusting the detunings of the cooling lasers. This allows us to disentangle the reactions that begin with Ca$^+$ in the $^2$P$_{1/2}$-state from the ones where Ca$^+$ is in the $^2$D$_{3/2}$-state. Using time-of-flight mass spectrometry, we determine independent reaction rate constants for Ca$^+$ in both electronically excited quantum states.

physics.atom-ph↗

arXiv2019

Using think-aloud interviews to characterize model-based reasoning in electronics for a laboratory course assessment

Models of physical systems are used to explain and predict experimental results and observations. The Modeling Framework for Experimental Physics describes the process by which physicists revise their models to account for the newly acquired observations, or change their apparatus to better represent their models when they encounter discrepancies between actual and expected behavior of a system. While modeling is a nationally recognized learning outcome for undergraduate physics lab courses, no assessments of students' model-based reasoning exist for upper-division labs. As part of a larger effort to create two assessments of students' modeling abilities, we used the Modeling Framework to develop and code think-aloud problem-solving activities centered on investigating an inverting amplifier circuit. This study is the second phase of a multiphase assessment instrument development process. Here, we focus on characterizing the range of modeling pathways students employ while interpreting the output signal of a circuit functioning far outside its recommended operation range. We end by discussing four outcomes of this work: (1) Students engaged in all modeling subtasks, and they spent the most time making measurements, making comparisons, and enacting revisions; (2) Each subtask occurred in close temporal proximity to all over subtasks; (3) Sometimes, students propose causes that do not follow logically from observed discrepancies; (4) Similarly, students often rely on their experiential knowledge and enact revisions that do not follow logically from articulated proposed causes.

physics.ed-ph↗

arXiv2018

Characterizing lab instructors' self-reported learning goals to inform development of an experimental modeling skills assessment

The ability to develop, use, and refine models of experimental systems is a nationally recognized learning outcome for undergraduate physics lab courses. However, no assessments of students' model-based reasoning exist for upper-division labs. This study is the first step toward development of modeling assessments for optics and electronics labs. In order to identify test objectives that are likely relevant across many institutional contexts, we interviewed 35 lab instructors about the ways they incorporate modeling in their course learning goals and activities. The study design was informed by the Modeling Framework for Experimental Physics. This framework conceptualizes modeling as consisting of multiple subtasks: making measurements, constructing system models, comparing data to predictions, proposing causes for discrepancies, and enacting revisions to models or apparatus. We found that each modeling subtask was identified by multiple instructors as an important learning outcome for their course. Based on these results, we argue that test objectives should include probing students' competence with most modeling subtasks, and test items should be designed to elicit students' justifications for choosing particular modeling pathways. In addition to discussing these and other implications for assessment, we also identify future areas of research related to the role of modeling in optics and electronics labs.

physics.ed-ph↗

arXiv2018

Transforming a large introductory lab course: impacts on views about experimental physics

Laboratory courses are key components of most undergraduate physics programs. Lab courses often aim to achieve the following learning outcomes: developing students' experimental skills, engaging students in authentic scientific practices, reinforcing concepts, and inspiring students' interest and engagement in physics. Some of these outcomes can be measured by the Colorado Learning Attitudes about Science Survey for Experimental Physics (E-CLASS), a research-based assessment that measures students' views about experimental physics. We used E-CLASS at the University of Colorado Boulder to measure learning outcomes during a course transformation process in which views about experimental physics were reflected in the learning goals. We collected over 600 student responses per semester from the large introductory laboratory course, both before and after implementing the course transformation. While we observed no statistically significant difference in overall post-instruction E-CLASS scores before and after the transformation, in the transformed course, student responses to three E-CLASS items that related to the goals of the transformation were more favorable than in the original course.

physics.ed-ph↗

arXiv2018

Initial impacts of the transformation of a large introductory lab course focused on developing experimental skills and expert epistemology

Recently, there has been increased attention to improving laboratory instruction at all levels. At the introductory level, research results have shown differing levels of success based on the nature of the desired learning outcomes. In response to these findings, the University of Colorado's introductory physics lab course was transformed to improve students' development of experimental skills and experimental physics epistemology. We describe the details of the transformation process and initial self-reported learning gains from the first implementation of the transformed course.

physics.ed-ph↗

arXiv2018

Correlating students' views about experimental physics with their sense of project ownership

Multiweek projects in physics labs can engage students in authentic experimentation practices, and it is important to understand student experiences during projects along multiple dimensions. To this end, we conducted an exploratory quantitative investigation to look for connections between students' pre-project views about experimental physics and their post-project sense of project ownership. We administered the Colorado Learning Attitudes About Science Survey for Experimental Physics (E-CLASS) and the Project Ownership Survey (POS) to 96 students enrolled in 6 lab courses at 5 universities. E-CLASS and POS scores were positively correlated, suggesting that students' views about experimentation may be linked to their ownership of projects. This finding motivates future studies that could explore whether these constructs are causally related.

physics.ed-ph↗

arXiv2018

Pathways to proposing causes for unexpected experimental results

Models of physical systems are used to explain and predict experimental results and observations. When students encounter discrepancies between the actual and expected behavior of a system, they revise their models to include the newly acquired observations, or change their apparatus to better represent their models. The Modeling Framework for Experimental Physics describes the process of matching measurements and observations to models by making revisions to resolve discrepancies. As part of a larger effort to create assessments of students' modeling abilities in the context of upper-division electronics courses, we used the Modeling Framework to develop and code think-aloud problem-solving activities centered on troubleshooting an inverting amplifier circuit. We observed that some participants iteratively and continuously made measurements and revisions if they could not immediately propose a cause for an observed discrepancy. This pathway has not been previously discussed in the Modeling Framework. In this paper, we discuss two episodes where students undergo this process to converge on a proposed cause post hoc. We conclude by discussing implications for a modeling assessment based on the observed modeling behavior.

physics.ed-ph↗

arXiv2018

The Modeling Framework for Experimental Physics: Description, development, and applications

The ability to construct, use, and revise models is a crucial experimental physics skill. Many existing frameworks describe modeling in science education at introductory levels. However, most have limited applicability to the context of upper-division physics lab courses or experimental physics. Here, we discuss the Modeling Framework for Experimental Physics, a theoretical framework tailored to labs and experimentation. A key feature of the Framework is recursive interaction between models and apparatus. Models are revised to account for new evidence produced by apparatus, and apparatus are revised to better align with the simplifying assumptions of models. Another key feature is the distinction between the physical phenomenon being investigated and the measurement equipment used to conduct the investigation. Models of physical systems facilitate explanation or prediction of phenomena, whereas models of measurement systems facilitate interpretation of data. We describe the Framework, provide a chronological history of its development, and summarize its applications to research and curricular design. Ultimately, we argue that the Modeling Framework is a theoretically sound and well-tested tool that is applicable to multiple physics domains and research purposes. In particular, it is useful for characterizing students' approaches to experimentation, designing or evaluating curricula for lab courses, and developing instruments to assess students' experimental modeling skills.

physics.ed-ph↗

arXiv2017

Pulsed versus continuous wave operation of a ring Stark decelerator

Stark deceleration is a technique that uses time-varying inhomogeneous electric fields to decelerate polar molecules for various molecular beam and trapping experiments. New ring-geometry Stark decelerators with continuously varying voltages offer a method to produce a more intense source of molecules in a technique called traveling-wave Stark deceleration. However, this type of deceleration is more experimentally challenging than the more typically used crossed-pin geometry decelerators with pulsed voltages. Here, we present an experimental realization of a ring-geometry Stark decelerator using either continuously varying or discrete voltages. Pulsed-ring Stark deceleration using discrete voltages is easier to implement and, under certain circumstances, is more efficient than traveling-wave Stark deceleration. A comparison of experimental and simulated results between traveling-wave and pulsed-ring Stark deceleration is presented along with a simple model for determining when each mode is more efficient.

physics.chem-ph↗

arXiv2017

Student ownership of projects in an upper-division optics laboratory course: A multiple case study of successful experiences

We investigate students' sense of ownership of multiweek final projects in an upper-division optics lab course. Using a multiple case study approach, we describe three student projects in detail. Within-case analyses focused on identifying key issues in each project, and constructing chronological descriptions of those events. Cross-case analysis focused on identifying emergent themes with respect to five dimensions of project ownership: student agency, instructor mentorship, peer collaboration, interest and value, and affective responses. Our within- and cross-case analyses yielded three major findings. First, coupling division of labor with collective brainstorming can help balance student agency, instructor mentorship, and peer collaboration. Second, students' interest in the project and perceptions of its value can increase over time; initial student interest in the project topic is not a necessary condition for student ownership of the project. Third, student ownership is characterized by a wide range of emotions that fluctuate as students alternate between extended periods of struggle and moments of success while working on their projects. These findings not only extend the literature on student ownership into a new educational domain---namely, upper-division physics labs---they also have concrete implications for the design of experimental physics projects in courses for which student ownership is a desired learning outcome. We describe the course and projects in sufficient detail that others can adapt our results to their particular contexts.

physics.ed-ph↗

arXiv2017

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 ($N_{institutions}=75$ and $N_{students}=7167$) 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.

physics.ed-ph↗