arXiv subjects

David J. Webb

Publications and source records attributed to David J. Webb.

21 records · Page 2Linked to original sources

arXiv2020

Relative impacts of different grade-scales on student success in introductory physics

In deciding on a student's grade in a class, an instructor generally needs to combine many individual grading judgments into one overall judgment. Two relatively common numerical scales used to specify individual grades are the 4-point scale (where each whole number 0-4 corresponds to a letter grade) and the percent scale (where letter grades A through D are uniformly distributed in the top 40% of the scale). This paper uses grading data from a single series of courses offered over a period of 10 years to show that the grade distributions emerging from these two grade scales differed in many ways from each other. Evidence suggests that the differences are due more to the grade scale than to either the students or the instructors. One major difference is that the fraction of students given grades less than C- was over 5 times larger when instructors used the percent scale. The fact that each instructor who used both grade scales gave more than 4 times as many of these low grades under percent scale grading suggests that the effect is due to the grade scale rather than the instructor. When the percent scale was first introduced in these courses in 2006, one of the authors of this paper, who is also one of the instructors in this data set, had confidently predicted that any changes in course grading would be negligible. They were not negligible, even for this instructor.

physics.ed-ph↗

arXiv2018

Pondering zeros: analysis of a decade of blanks and missed quizzes

When assessing student work, graders will often find that some students will leave one or more problems blank on assessments. Since there is no work shown, the grader has no means to evaluate the student's understanding of a particular problem, and thus awards 'zero' points. This practice punishes the student behavior of leaving a problem blank, but this zero is not necessarily an accurate assessment of student understanding of a particular topic. While some might argue that this practice is 'fair' in that students are aware that they can't receive points for problems they don't attempt, we share evidence that this practice unequally impacts different student groups. We analyze 10 years of UC Davis introductory physics course databases to show that different groups of students (by gender, racial/ethnic group, first generation, etc.) skip problems, and entire exams at different rates. We also share some implications for grading and teaching practices.

physics.ed-ph↗

arXiv2016

Learning Concepts First: A Course Structure with Improved Educational Outcomes in the Short, Medium, and Long Terms (Especially for Minority Groups Underrepresented in Physics)

An active learning physics course (treatment) was re-organized in an attempt to increase students' problem solving abilities. This re-organized course covered all of the relevant concepts in the first 6 weeks with the final 4 weeks spent in practice at solving complicated problems (those requiring students to use higher order cognitive abilities). A second active learning course (control) was taught in the same quarter by the same instructor using the same curricular materials but covering material in the standard (chapter-by-chapter) order. After accounting for incoming student characteristics, students from the treatment course scored significantly better than the control for two outcome measures: i) the final exam and ii) their immediately subsequent physics course. More importantly, students from minority groups who are underrepresented in physics had final exam scores as well as class grades that were indistinguishable from the rest of their class if and only if they were in the treatment class. Finally, many of the students in this cohort took a Concepts First course in their third quarter of introductory physics. The students who took at least one Concepts First course are found to have significantly higher rates of graduation with a STEM major than those students from this cohort who did not take a Concepts First course.

physics.ed-ph↗