## Using Tracker as a Pedagogical tool framed (3 parts) using Pedagogical and Professional – experience Repertoire (PaP-eR)

Topic: Dynamics of Motion (Sliding Example) Kinematics Scenario
Name: lookang
School: etd
Related Concepts/Ideas from other topic(s):Kinematics,
readings on PaP-eR Loughran, Berry, & Mulhall (2012). Understanding and developing science teachers’ pedagogical content knowledge, 2nd Edition https://www.sensepublishers.com/media/1219-understanding-and-developing-science-teachers-pedagogical-content-knowledge.pdf
password network: ST LT networks on OPAL
password required RGS mentoring group https://www.edmodo.com/home#/group?id=12031459

## Part 1: Explicit link to the Content Representation (CoRe)

### Important Science Ideas / Concepts

1. Modeling, teaching them how to fish instead of fish for them
2. Friction is a force
3. Initial velocity
4. Cartesian coordinate system (vector and scalar, why have negative sign etc)
5. Measurement: Calibration Length
6. Evidence based explanations and argumentation

1. Physics is applicable to real world and fun.
2. Modeling is a key practice of Science Education

1. Why does a push(force) mean when we say it acts for a short time?
2. Friction is present everywhere but i cannot see what it means.
3. When do i know friction act on the motion or not.

### Suitable teaching approaches/strategies and particular reasons for using these to engage with this idea

1. Teacher demo dynamic modelling approach with show and tell, some interactive quiz to check for understanding
2. computer lab hands-on activities to allow learning through experience

### Specific ways of monitoring students’ understanding or confusion around this idea

1. some interactive quiz to check for understanding
2. a performance task of a similar activity using the modeling technique shared
3. discussion in school flip-classroom structure, or just use a blog like http://weelookang.blogspot.sg/ for comments and discussions in Web 2.0 ways, with incorporating cyberwellness, digital literacy etc infused.
4. series of questions (Socratic dialogue) directed at clarifying students’ assumptions, claims and explanations can help develop their understanding of the concepts

## Part 2: Synopsis of the Practice

1. Open Tracker using the Start|Programs|Tracker and click it to launch the program already installed from https://www.cabrillo.edu/~dbrown/tracker/
2. Click on the 3rd icon from the left, Open the OSP digital library browser and a pop up appears of which you can navigate to the Singapore Digital Library Collection
3. select the video resource to be inserted into Tracker by navigating to http://iwant2study.org/lookangejss/02_newtonianmechanics_3dynamics/trz/videos/Push n Constant Deceleration Model.mp4 found in folder 02_newtonianmechanics_3dynamics/trz/videos/Push n Constant Deceleration Model.mp4
4. the video is loaded successfully into Tracker
5. Guide the students to Calibrate the video, selecting the first Calibration Stick
6. Since this video has a 1 metre ruler beside the cart, drag the + ends + of the Calibration Stick to coincide with the ruler in the video a shown. Click on the 100.0 (default setting of 100 arbitrary units)and change it to 1.000 instead for the video case of 1 metre and press the keyboard "enter" key to accept the change in calibrated length made.
7.  Select the axes and drag the centre to a suitable starting position of your choice, recommended is the centre of the cart or something you can very easily track.
8. We are ready! Create a new Point Mass which will be used to track the position of the cart
9. in Mass A mode, press on the keyboard the 'Shift' key and a special aiming cursor appears and you are ready to track.
10. with the left hand finger pressing on the 'shift' key and now aim at the centre of the cart and with right hand mouse left click, Tracker automatically track the object and progress to the next frame so you can just keep on mouse left click on the object until the end of the video at frame 87.
11. as shown, Tracker shows all the data points you tracked, and on the right, there is a Plot of x versus t, which we will focus on.
12. Model A: constant velocity ?
13. to create models, select the Create|Dynamics Particle Model| Cartesian and automatically a Model A appears
14. Select the Model Builder pop up to start modeling!
15. in this model, you can do a Data Analysis of the points just as the cart moves off to determine the initial velocity, can you get roughly  vx = 0.5927 m/s? Key this vx value and test your model.

16.  you can now observe the effects of this constant velocity model, what is discrepant about the model proposed versus the actual motion? Hint: the starting time t can be further proposed as t = 0.167 s.
17. discuss the strength(s) and weakness(es) of this model. for example, you might say the strength is the motion is closely match from 0.167 < t < 0.8. weakness could be t >1.00 seems to be not well represented.
18. Model B: constant deceleration ?
19. Dissatisfied with Model A, constant velocity, let refer to step 13, create a new Model B which perhaps is a constant deceleration model. Again you should do some Data Analysis of the real motion to determine a suitable negative acceleration that can represent the motion from t > 0.167 s. You are recommended to try this on your own and refer to the hints if need. a possible model could be x = -0.1351, vx = 0.7215 and fx = (m)(ax) = (1)(-0.1268*2)
20.  As you build this model, there are a lot of things you can experience such as this model is valid only for t > 0.167 s, the values x = -0.1351 and vx = 0.7215 can be determined through intelligent trial and error, reflects the fictitious point the model predicts in could be at t =0 etc.
21. You could also produce a different model that uses the Start Frame exactly at the time of t = 0.167 s
22. Model D: Push and Friction
23.  A more robust model is suggested below that can account for the Push and Friction in computational thinking methodology . 1. Add new Parameters such as Push and Friction. Push is to be determine by evidence based trial and error, Friction = -0.1268*2 determined by Data Analysis. Next, key in force in x direction the following line if(t<0.167,0,if(t<0.172,Push,Friction)) with means if time is lesser than 0.167, fx is 0 ( newton's 1st law), if 0.167 < t < 0.172 fx is a Push defined in parameters, t > 0.172 fx is 0 again  ( newton's 1st law).
24. To get a comparison graph of Point Mass A and the Models, right click on the right panel and select compare with option of the desired Model(s).
25. To be explicit the meaning of this Model D Push initially for duration of dt =0.05 s arbitrarily set by me as an close appropriation to the real motion, we showed Physics of Dynamics Push and Friction can be easily experienced by student learning by doing supported with teacher explanation.
26. I hope you can see the power of learning by modeling and drop me a Google+ comment below and let's network learn together.