Can a Combination of Hands-on Experiments and Computers Facilitate Better Learning in Mechanics?Jonte Bernhard
ITN, Campus Norrköping, Linköping University, S-60174 Norrköping, Sweden
Partial financial support from the Swedish National Agency for Higher Education, Council for Renewal of Higher Education, is gratefully acknowledged. Part of the research reported in this paper was done while the author was employed at Högskolan Dalarna, Borlänge, Sweden.
Microcomputer-Based Laboratories (MBL) have been successfully used to promote conceptual growth in mechanics understanding among preservice teachers and engineering students. In MBL laboratories students do real hands-on experiments where real-time display of the experimental results facilitates conceptual growth. Thus students can immediately compare their predictions with the outcome of an experiment, and students' alternative conceptions can thus successfully be addressed. We also report from a case where only MBL-technology was implemented, but the students were not asked to make predictions. As a result "misconceptions" were not confronted and conceptual change was not achieved among "weak" students.
Acquiring a conceptual understanding of mechanics has proven to be one of the most difficult challenges faced by students (for a good overview see McDermott 1998). Studies by many different researchers have shown that misleading conceptions of the nature of force and motion, which many students have, are extremely hard to overcome. These strong beliefs and intuitions about common physical phenomena are derived from personal experience and affect students' interpretation of the material presented in a physics course. Research has shown that traditional instruction does very little to change students' "common-sense" beliefs (see for example McDermott 1998; Hestenes et al. 1992; Hake 1997; Bernhard 2000a).
For some decades sensors attached to a computer have been used in most experimental physics research laboratories. The attachment of a sensor to a computer creates a very powerful system for the collection, analysis and display of experimental data. In this paper I report on cases where hands-on experiments have been combined with a microcomputer-based system for the collection and display of experimental data. This MBL concept has proved to be a very powerful educational tool.
Figure 1. Typical setup of a MBL-experiment. A low-friction cart is pushed towards a motion sensor. A fan unit attached to the cart provides an approximately constant force in a direction opposite to the initial movement and the cart will thus change its direction of motion. The results are shown in Figure 2. Note that the fan unit provides a visible force.
In an MBL laboratory students do real experiments, not simulated ones, using different sensors (force, motion, temperature, light, sound, EKG ...) connected to a computer via an interface. One of the main educational advantages of using MBL is the real-time display of experimental results and graphs thus facilitating direct connection between the real experiment and the abstract representation. Because data are quickly taken and displayed, students can easily examine the consequences of a large number of changes in experimental conditions during a short period of time. The students spend a large portion of their laboratory time observing physical phenomena and interpreting, discussing and analysing data with their peers. The MBL context adds capacity and flexibility that, to be exploited requires the laboratory to be reconceptualised, giving students more opportunity to explore and learn through investigations (Tinker 1996; Thornton 1997b). This makes it possible to develop new types of laboratory experiments designed to facilitate better student learning and to use laboratories to address common preconceptions. To take full advantage of MBL the educational implementation is important, not the technology! Active engagement is important!
Figure 2. Results of the MBL laboratory shown in Figure 1. The position, velocity and acceleration as functions of time are displayed. A common misconception is that the cart has zero acceleration at the turning point. Another common misconception is that the acceleration is in the direction of motion (see the poor results on the pre-test for "coin acceleration" in Figure 4). By asking the students to make a prediction and sketch the s(t), v(t) and a(t) graphs before the experiment and by the rapid display of the experimental results these misconceptions can effectively be addressed.
Figure 3. Results from an MBL-experiment with two colliding carts with equal and unequal masses respectively. Force sensors are mounted on top of each cart. The graphs show the forces measured by the sensors during the collision and the area below curves. Note the time scale. Most students are surprised to discover that the forces are equal when the carts have different masses (see "3rd collision" pre-test in Figure 4).
Implementation of MBL laboratories
The physics department at Högskolan Dalarna started using MBL in 1994/95. Laboratories using MBL-technology have been introduced in most physics courses. Below will be described the results of implementations of MBL in "active engagement" mode (Cases 1 and 2) and in mainly "formula verification" mode (Cases 3 and 4).
Cases 1 and 2
Case 1: An early implementation of MBL laboratories (Preservice teachers 1995/96) in a course for preservice science teachers (preparing for teaching grades 4-9 in Swedish schools). Case 2: A full implementation of MBL laboratories (Mechanics I 1997/98 for Engineering students) and some other reforms (see Table 1). This curricular reform also included changes to the advanced mechanics course (Mechanics II). The reformed advanced mechanics course is described elsewhere (Bernhard 1998, 1999). In both cases 1 and 2 there were about 40 students in the course.
The educational approach (Bernhard 2000b) taken in both cases was inspired by, but not identical to, the approach taken by Sokoloff et al. (1998) in RealTime Physics (see also Thornton 1997b, and references therein) and in case 2 also by the "New Mechanics" paper by Laws (1997). Laboratories were written in Swedish by the author.
Case 3: Preservice teachers 1998/99
(~ 30 students)
Case 4: Preservice teachers 1999/2000
(~ 25 students)
Table 1. Laboratories (4 hours) used in the Mechanics I course in 1997/98.
The Force Concept Inventory (FCI) developed by Hestenes et al. (1992) and the Force and Motion Conceptual Evaluation (FMCE) developed by Thornton and Sokoloff (1998) were used as instruments for evaluating students' conceptual understanding. The data from the FMCE-test were analysed using the Conceptual Dynamics method developed by Thornton (1997a). Using this method, student views (for example force-follows-velocity view or physics view) can be assigned.
Cases 1 and 2
As can be seen in Tables 2 and 3 and in Figures 4 and 5 the students in cases 1 and 2 have gained a much better conceptual understanding of mechanics than students in traditionally taught courses. A high fraction of the students have acquired a Newtonian view and a low fraction of students hold a force-follows-velocity view after instruction. The students in Mechanics I (case 2) performed significantly better on traditional problems in the final examination, than the students did in earlier similar courses.
In this course male and female students also had the same normalised gains.
Table 2. Results of pre- and post-testing using Force Concept Inventory (Hestenes et al. 1992) on different student groups.
|Course||Year||Main student body||Method||Pre-test average||Post-test average||Gain (G)||Normalised gain (g)|
|Mechanics I||97/98||Engineering||Full MBL +||29%||72%||43%||61%|
|Preservice||98/99||Preservice science teachers (grades 4-9)||
|Preservice||99/00||Preservice science teachers (grades 4-9)||
Some MBL pedagogy
The students in case 3 did not perform as well as in cases 1 and 2, but somewhat better than students in traditionally taught courses did. As can be seen in Figure 5 almost the same fraction of students hold the force-follows-velocity view after instruction as before instruction. By eliminating the active engagement part from the laboratories the preconceptions of the students believing in this view were not reached.
There were also large differences in gains between male (higher gain) and female (lower gain) students. A higher fraction of female students believed in a force-follows-velocity view after the course than before instruction!
The students in case 4 performed similarly to the students in case 3, except for a much better performance in the Newton's 3rd law conceptual areas (see Figure 6 below). The difference in gains between male and female students was smaller than in case 3.
Microcomputer-Based Laboratories (MBL) in an active engagement approach is proven to be an effective way of fostering conceptual change in mechanics. The conceptual understanding is long-lived (Bernhard 2000c). MBL is good both for preservice teachers and engineering students. The combination of hands-on experiments and the microcomputer-based measurement system is a very powerful educational tool and according to Euler and Müller (1999) one of the few educational approaches in physics using computers which is reported to have positive effects on student learning. Students need to make use of as many senses as possible in their meaning making and thus approaches which make use of both hands-on and high-technology tools seem to be very effective (see also Otero 2000). In a well implemented MBL-approach MBL is used as a technological tool and a cognitive tool.
However the MBL-approach can be misunderstood and implemented as a technology only approach. When implemented without sound pedagogy, MBL is only marginally better than "traditional" teaching. Pedagogy is more important than technology! The personal preconceptions students hold before instruction must be addressed in some way during a course. Asking students to make predictions before an experiment is done is one way to both confront "misconceptions" and to reinforce scientific views.
It is also very important to focus on the teacher's pedagogical views since they can distort/destroy the implementation of an educational approach (see also for example Sassi 2000). Probably it is as difficult to change a teacher's view/conception of teaching, as it is to change a student's view/conception of the world.
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