![[Image of Web page]](image01.gif)
Jon M Pearce, School of Physics and Science Multimedia Teaching Unit, University of Melbourne, Parkville, Vic 3052, Australia. Phone +613 9344 8072 Fax: +613 9347 4783 j.pearce@physics.unimelb.edu.au Home Page [HREF1]
Michelle K Livett, School of Physics, University of Melbourne, Parkville, Vic 3052, Australia. Phone +613 9344 8071 Fax: +613 9347 4783 m.livett@physics.unimelb.edu.au
World Wide Web, Tertiary, Physics Education, Video analysis, Java, Australia
At AusWeb96 we reported on a development project to provide a sophisticated Java video analysis tool to students studying undergraduate physics (see [HREF 1]). Students will use the tool as part of a Web site on analysing videos of real-world events in order to help understand the physics behind them. The analysis tool, MotionWorkshop, also provides sophisticated modelling capabilities enabling students to construct spreadsheet-style models to test against the videoed events.
This paper reports on the progress of the project as well as some of the difficulties encountered along the way. The project is ongoing and preliminary trialling with students will take place during this year.
A continuing challenge to physics educators is students' tendency to quarantine the physics understanding they gain during formal instruction from their everyday lives (Arons 1990, McDermott 1991, Redish 1994). This tendency comes, in part, from the difficulty of bringing the excitement of the physics of the real world into a lecture theatre: trampolines, pole vaulters and space shuttles just don't fit! A solution in the past has been to perform demonstrations which illustrate the concepts being addressed. Whilst such demonstrations are of great value and to be encouraged, they are usually not accessible for students to play with after the lecture when they might like to explore some "what if" questions.
These two issues - the difficulty of bringing real-world physics to students and the one-off nature of lecture demonstrations - are the target of a current CAUT-funded project entitled Real-World Physics. The project aims to provide first year undergraduate students with a sophisticated Web-based analysis tool which allows them to analyse video-clips. The video-clips produced are of real events, and of lecture demonstrations. Although other examples of video analysis software exist (see, for example CamMotion [HREF2], VideoGraph [HREF3], VideoPoint [HREF4], Learning in Motion [HREF5] and World in Motion [HREF6]), they do not offer the same spreadsheet modelling facilities of this project, nor are they Web-based.
The software being developed comprises Web-based learning modules within which students view closely, and analyse, short video segments of real-world events or key lecture demonstrations. A typical event might be the motion of a long-jumper or the swing of a golf club. The video analysis will be carried out within MotionWorkshop, a Java applet. The applet is linked to a World Wide Web document which provides the learning framework for students' video analysis including motivating questions, background information and suggestions for analysis.
Analysis using the applet will involve the students tracking the motion of a point or points on the moving object by clicking, frame by frame, on the video image on the screen. The resulting data will be recorded into an on-line spreadsheet which will automatically calculate values of velocity and acceleration. From the spreadsheet several functions will be controlled:
Suitable spreadsheet quantities will also be displayed on a vector display. Due to the nature of derived vector quantities, this display will be three-dimensional, and rotatable so that different views of the vectors can be seen.
An unusual and innovative feature of the spreadsheet will be its three-dimensional nature. Any quantity in the spreadsheet can be defined as a 3-d vector. True 3-d vector operations will be available as regular spreadsheet formulas enabling students to manipulate and visualise quantities in 3-d space in a manner not previously possible.
The spreadsheet has also been designed to simplify the generation of data using numerical modelling techniques. This will allow students to enter a mathematical model for a motion they are studying and see the model's results side-by-side with the analysed video data. This form of modelling is a powerful method of "completing the loop" in helping understand motion. It enables students to set up their own models of the causes of motion, and compare the outcomes with reality.
These analysis activities will be coupled with "virtual interviews" with people to whom the physics under examination is important. Through these we hope to provide students with insights into how the physics ideas apply in practice. These interviews will be presented in the Web document and, although pre-recorded and limited in scope, will help students appreciate the fact that real people have to think about real physics in real life.
By analysing real-world situations, and viewing them via these multiple representations, students will deepen their understanding of physics principles. Gaining insights from videoed interviews will enhance students' perception of the relevance of physics to their own experience.
To give an idea of exactly what the student activities involve, the following is a brief outline of a student's progress through the learning package.
Web Site. The student begins by accessing the project's Web site and selecting the assignment she wishes to study. In this example, it involves analysing the motion of rotating clubs as a juggler tosses them from hand to hand and then modelling the motion by using the spreadsheet. The Web document presents the background physics, the requirements of the assignment, presents a short video of the motion to be analysed and solicits some feedback from the student (via a Web form) concerning her initial conceptions.
MotionWorkshop. The student's next task is to launch the MotionWorkshop applet (from the Web site) and call up the video segment for analysis. She will enter position data for one of the juggler's clubs by clicking on the club in each frame of the video. These data are automatically entered in to the spreadsheet from where she can elect to display columns of data representing various parameters, such as velocity or acceleration.
She might choose next to plot a graph of one of her quantities. In addition, she might decide to use the spreadsheet to calculate a derived quantity, kinetic energy maybe, and display its values on a graph.
![[MotionWorkshop screen]](image02.gif)
In order to understand how the acceleration varies during the motion, she might choose to display vectors (instead of the graph) and manipulate them on-screen. A video of the side view of the motion will enable her to construct a set of angular velocity vectors pointing in the third dimension and explore how these vectors change during flight.
Having formed an understanding of the nature of this motion, the student can begin to construct a numerical model by entering the relevant equations of motion into new columns in the spreadsheet. The data she constructs in this way can be overlaid on the original motion to test its validity. MotionWorkshop will provide easy ways for her to change variables in her model and immediately see the effects. "What if" type questions will be raised whereby she will be motivated to consider variations on the motion and test her hypotheses by calling up a related movie clip and again comparing this real motion to her analysis.
Reflecting on Learning. Having finished exploring the motion in the analysis tool, she will record and consolidate her learning by making entries into a prepared paper-based logbook under headings such as "physics understanding developed", "equations used", "modelling strategies" and "what-if questions".
![[Short Interview with a sprinter (1MByte)]](image03.gif)
Interview the Juggler. The final part of this assignment
will allow her to "interview" the juggler about how
he uses a knowledge (or lack of) whilst juggling. She will choose
from a variety of questions set up on the Web and view short video-clips
of the juggler responding. Many of these questions pick up on
the "what if" theme and might inspire further analysis. (The image opposite links to a movie of the juggler being interviewed about the difference between juggling balls and clubs. File size = 3.4MByte).
A final reflection. Back in her logbook, she will make final reflective comments about what she has learned, problems encountered and her thoughts on the process.
Throughout this process, which will be done via the Web, or from CD, at university or at home, the student will be making decisions and seeing their immediate consequences. She will be tempted to explore and to link the world of analytical physics to real world scenarios. The logbook produced will be a record of what she has done as well as providing feedback to us about learning outcomes and student impressions.
The nature of the student activity while using this software is one of interactive engagement in a task. Students will be continually making decisions about what to measure, how to calculate quantities, which features to display.
Whilst doing this, they will be viewing motions using multiple representations of data. The data they view will be presented as video, numbers, graphs and vectors. Each of these will be linked on the screen to help reinforce their equivalence. This technique of multiple representations is a promising way of helping students develop the necessary analytical skills required in physics (Beichner 1990, Escalada and Zollman (in press)).
The numerical modelling aspects enable students to turn an analysis situation around into a predictive one. Rather than describe an existing motion, they are put in the position of defining the physics that determines the motion. This can be a demanding task, but one which is an important part of any physics learning.
Evaluations of the use of this software will endeavour to determine
how these features support students' learning and promote a deeper
understanding of physics principles and applications.
Turning dreams into reality is often fraught with problems, and the development of this software was no exception. The task, begun in 1996, was a substantial one for several reasons:
Allied with the complexity of the package was the need for academic oversight of each aspect of the project. The fact that academic input cannot be full-time due to other demands like teaching, research, and administration, at times has retarded progress in the project development. A brief description of each aspect of the integrated project will highlight the need for academic input.
Video: Selection of subjects to provide appropriate video material requires understanding of the desired learning outcomes of the project. The package is intended to provide students with the opportunity to develop their own understanding of motion, and to allow ample opportunity for them to confront those barriers to understanding which have been highlighted by physics education research. The choices are not simply what will look good on the screen, but what will comprise a beneficial sequence for students' learning, requiring academic judgement.
There are also overheads associated with interacting with potential video subjects. This has at times included extended negotiation periods as participants need to be reassured about their involvement in a very public project.
Software: There has been an enormous time commitment to program design. This is due to the complexity of the package, with the dual requirements that the applet have multiple, powerful and flexible tools, while its design makes the use of these tools intuitive and straightforward.
HTML: Here is where the learning package's framework of physics content and student assignments is found. These learning materials are written by physics academics and lie within a structure designed by an HTML programmer in collaboration with those academics. Decisions about the types of interactions students would be engaged in, the inclusion of forums, email feedback, posting questions for teachers' answers and for other students' perusal, need to be made by the academics working on the project.
Graphics: The graphical design needs to serve the needs of the students, in helping them to navigate their way through both the HTML document and the Java applet. It requires less extensive liaison between designers and academics at each stage.
Our experience has highlighted the demands placed on academic staff involved in the execution of such a project. There is a clear need for significant involvement of an academic team in each facet of the project development, limiting the possibility of sub-contracting out various aspects of the project.
The newness of Java was a difficulty over which we had least control. Our decision to use Java, rather than an established language such as C++, was a carefully considered one based on the benefits of cross-platform operation without installation, and, of course, the requirement to give students access to the whole package via the Web. However, although the hype of this new language was extreme, the reality brought many significant obstacles.
The most significant obstacle was that of compatibility. Java applets of this type require a 32 bit operating system and will hence not run effectively under Windows 3.1. This leaves the common operating systems supported as Windows NT or 95, Macintosh and Unix. Current versions of applets created on a Unix workstation (using Java Development Kit 1.1) will not run exactly the same on the Windows and Macintosh platforms. The differences range from minor matters of appearance, to crucial problems of applets not running at all!
The execution speed of Java is also problematic. It has been measured to be about 1.5 times slower than C, when the applet is pre-compiled using a Just-In-Time compiler (negating the cross-platform download feature). However, this performance is even slower when the applet is executed through a browser, with Netscape being about 5 times slower than Internet Explorer, running in Windows 95! For a discussion on the execution speed of Java applets see [HREF 7].
Many aspects of the Abstract Windows Toolkit (a part of the Java programming environment) produce objects that just don't work in some situations. These objects are components like buttons, scroll bars and dialogue boxes, and must all be tested in situ within the applet being developed.
A serious current impediment to using Java for video analysis is that no class libraries yet exist to control QuickTime movies from within an applet. Our temporary fix for this has been to store the movies as a sequence of gif files, to be replaced by QuickTime movies when the software is available. This solution makes the movement from frame to frame very slow (at best 5 seconds per frame using Internet Explorer 3.01, more than a minute using Netscape 3.01!).
Nevertheless, our judgement was that enough support was being given to Java to secure its future, and to promise that many of the problems mentioned above would be rectified in future releases. We have seen this happening as we have witnessed numerous improvements as the various versions of the Java Development Kit have been released. Hence our decision was to stick with Java, even if it meant using a compiled version of our software in the short term until speed and compatibility problems are ironed out.
Although there have been some difficulties in the development of the package, the project has generated great interest and excitement among academics across a diverse range of disciplines. The presentation will demonstrate the software at its current (unpolished!) stage of development, display the underpinnings of its design and outline how students will use it as a learning environment.
Videos of the straight-line motion of an Olympic-standard sprinter accelerating from a variety of starting positions, a juggler executing intricate patterns of parabolic projectile motion, some electromagnetic demonstrations and falling object demonstrations are now available. Also complete are interviews with the protagonists focussing on what they have to do to achieve the motion seen in the video. The project in its current form can be accessed from the project site [HREF 8].
Several aspects of the applet are functioning well. Due to the obstacles outlined earlier we have decided to carry out initial trials of the software using a stand-alone compiled version. This will enable us to carry out formative evaluation of the user interface while continuing with the applet development.
Evaluation will focus on the ease of use of the applet interface, the role of the package in deepening the learning of students and its success in countering their perception of physics having a place only outside the real world.
In spite of the challenges of developing a complex project in a very immature programming language, the efforts are bearing fruit and the software is entering its preliminary testing phase. Much interest has been generated by this project; those wishing to follow its progress should look at the project site [HREF 8].
R J Beichner, The Effect of Simultaneous Motion Presentation and Graph Generation in a Kinematics Lab (1990), J. Res. Science Teach. 27, 803-815.
L T Escalada and D Zollman, An Investigation of the Effects of Using Interactive Video in a Physics Classroom on Student Learning and Attitudes, J. Res. Science Teach. in press.
L C McDermott, Millikan Lecture 1990: What we teach and what is learned - Closing the gap (1991), Am. J. Phys. 59, 301-315.
E F Redish, Implications of cognitive studies for teaching physics (1994), Am. J. Phys. 62, 796-803.
Jon M Pearce and Michelle K Livett ©, 1997. The authors assign to Southern Cross University and other educational and non-profit institutions a non-exclusive licence to use this document for personal use and in courses of instruction provided that the article is used in full and this copyright statement is reproduced. The authors also grants a non-exclusive licence to Southern Cross University to publish this document in full on the World Wide Web and on CD-ROM and in printed form with the conference papers, and for the document to be published on mirrors on the World Wide Web. Any other usage is prohibited without the express permission of the authors.