McDermott, L. C., Rosenquist, M. L., & van Zee, E. H.

Tijdschrift/boek

American Journal of Physics, vol. 55, nr 6, pp. 503-513, 1987.

Abstract

Some common errors exhibited by students in interpreting graphs in physics are illustrated by examples from kinematics. These are taken from the results of a descriptive study extending over a period of several years and involving several hundred university students who were enrolled in a laboratory-based preparatory physics course. The study is partly motivated by the conviction that facility in drawing and interpreting graphs is of critical importance for developing and understanding many topics in physics.

Subsequent testing indicated that the graphing errors made by this group of students are not idiosyncratic, but are found in different populations and across different levels of sophistication. This paper examines two categories of difficulty identified in the investigation: difficulty in connecting graphs to physical concepts and difficulty in connecting graphs to the real world. Specific difficulties in each category are discussed in terms of student performance on written problems and laboratory experiments. A few of the instructional strategies that have been designed to address some of these difficulties are described.

Difficulties in connecting graphs to physical concepts:

Discriminating between slope and height (and difference between v/t and Dv/Dt)

1. Interpreting changes in height and changes in slope
2. Relating one type of graph to another
3. Matching narrative information to graph
4. Interpreting the area under a graph

Difficulties associated with connecting graphs to the real world are:

1. Representing continuous motion by a continuous line
2. Separating the shape of a graph from the path of the motion
3. Representing negative velocity
4. Representing constant acceleration
5. Distinguishing between different types of motion graphs

Instructional strategies that have been designed to address some of these difficulties are:

Grafieken in andere contexten, bijv. massa-volume of heat transferred- temperature rise. En hierbij voortdurend vragen over betekenis van physical quantities represented by the coordinates, slope and area en vragen naar welk gedeelte van de grafiek een antwoord geeft op een gesteld probleem.

1. Geef drie grafieken met precies dezelfde vorm, alleen eerste is s-t, tweede v-t en de derde a-t. Bij alle drie is beginsnelheid 10 m/s en de vraag is de snelheid na 9 sec.
2. Expliciet vragen om vertalen en interpreteren van allerlei grafische representaties (ticker, balletje op enkele plaatsen langs een helling met klokje erbij, etc.).