Abstract
In this article, we present several modifications to the Test of Understanding Graphs in Kinematics. The most significant changes are (i) the addition and removal of items to achieve parallelism in the objectives (dimensions) of the test, thus allowing comparisons of students' performance that were not possible with the original version, and (ii) changes to the distractors of some of the original items that represent the most frequent alternative conceptions. The final modified version (after an iterative process involving four administrations of test variations over two years) was administered to 471 students of an introductory university physics course at a large private university in Mexico. When analyzing the final modified version of the test it was found that the added items satisfied the statistical tests of difficulty, discriminatory power, and reliability; also, that the great majority of the modified distractors were effective in terms of their frequency selection and discriminatory power; and, that the final modified version of the test satisfied the reliability and discriminatory power criteria as well as the original test. Here, we also show the use of the new version of the test, presenting a new analysis of students' understanding not possible to do before with the original version of the test, specifically regarding the objectives and items that in the new version meet parallelisms. Finally, in the PhysPort project (physport.org), we present the final modified version of the test. It can be used by teachers and researchers to assess students' understanding of graphs in kinematics, as well as their learning about them. © 2017 authors. Published by the American Physical Society.
Highlights
A complete comprehension of kinematics concepts requires students to have an adequate understanding of graphs of position, velocity, and acceleration versus time in one dimension
The five objectives of this article are to (i) describe in detail the modifications made to the items of the test and the added distractors, (ii) analyze the difficulty, the discriminatory power, and the reliability of the added items, (iii) analyze the effectiveness of the added distractors in terms of their frequency selection and its discriminatory power, (iv) analyze the reliability and discriminatory power of the new version of the test as a whole and compare the values of the new version to the original test, and (v) illustrate the use of the new version of the test, presenting new analysis of students’ understanding that was not possible with the original version of the test, in the objectives and items that in the new version meet parallelism
(ii) Studies that have used the test to evaluate the effectiveness of new curricular material. These new materials incorporate a variety of approaches, including analysis of videos [7], a tutorial activity [8], and an open and interactive multimedia e-learning module [11]. (iii) Studies that have used the test to evaluate the relationship between the ability to interpret kinematics graphs and other variables of the population: A study analyzing the relationship between critical thinking and gender [12]. (iv) Studies that have used the test to investigate physics instructors’ pedagogical content knowledge in the subject of graphs of kinematics; for example, there is a study analyzing this knowledge of teaching assistants [9]
Summary
A complete comprehension of kinematics concepts requires students to have an adequate understanding of graphs of position, velocity, and acceleration versus time in one dimension. We realized we could not make conclusions about comparisons of students’ ability to select the corresponding graph from a graph (objective 5), since the original test includes items that require the selection of the velocity graph from the position graph, the acceleration graph from the velocity graph, and the velocity graph from the acceleration graph, but did not include the fourth possible option: the selection of the position graph from the velocity graph. We realized that we could not make complete conclusions about comparisons of students’ ability to select a textual description from different graphs (objective 6) since, for example, this objective did not include an item requiring a description of motion with a velocity increasing uniformly from an acceleration graph, an important topic in an introduction course. We realized that, in some items, the most
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