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NL 2010 02 21

Page history last edited by LFS 10 years, 3 months ago

Home -> Newsy Letters ->2010 February 21

February 21 2010


Animation – My thanks to David Cox.

1. Basic: To animate your worksheet with the built-in animator: Create a slider that you want to control the animation. For example, a slider for time. Right-click on the slider and choose “animation on”. The slider will begin to move. A pause button will appear in the lower left corner of the drawing pad. If you click on the pause button, the animation will stop and a play button will appear. Now you can change the type of animation and its speed. Right-click on the slider and choose “Object Properties” from the drop-down menu (at the bottom). On the Slider tab you will see Speed and Repeat (image at bottom of this page). The speed can be any positive number and the repeat can be increasing, decreasing or oscillating. Currently, the animation ALWAYS repeats.

Write me if you would like a YouTube video on how to do this.


A. Important tip for sliders. Always make the width of the slider a multiple of the length of the interval. The default width is 100. This is REALLY important for angle sliders. Make their width 72, 180 or 360 depending on whether you want your student to be able to select by 5°, 2° or 1°. Save yourself a lot of headache. The slider value may look like a whole number, but its actual value depends on width/interval.


2. Medium: Animation that doesn’t “run off”.  Currently you cannot use variables for the interval of a slider. So we often make the slider interval longer than we need to “cover” this problem.  This annoys the students (i.e. the bomb continues to fall “under the ground” or the timer runs on and nothing is happening).

Here is a way to have the built-in animation run exactly from “start to finish”.

1.       Suppose you want to animate time=t. If you have a variable for the totalTime=tT, then make a slider a=[0,1] and let t =a*tT.

2.       Suppose you want to animate time=t. If you have variables for the totalDistance= tD and the velocity=v, then make a slider a=[0,1] and let t =a*tD/v.

Write me if you would like a YouTube video on how to do this for a specific worksheet problem.


Question: What changes would you like to see in the built-in animator in the next version of GeoGebra? How important is this change to you:  Low Medium High?


3. Pbworks or Wikispaces user? You can embed GeoGebra interactivities with the built-in animator into your webpages. See: http://math247.pbworks.com/Simulator:-Space-Ball-Bounce or  http://mathfuture.wikispaces.com/Straightedge+and+compass+constructions+with+Geogebra  (way down at the bottom).

Write me if you would like a YouTube video on how to do either of these.


4. Pbworks user/administrator?  The fancy animator now works in pbworks! However, your network must allow javascript. Check and see: http://geogebrawiki.pbworks.com/ProbeVolcano   

IF you have any problems using this animator, please write me and tell me!

KEY: In your GeoGebra file, you must be animating with a slider named t0 from [0,1]  (as in 2 above, but rename it from “a” to “t0” – see more details at bottom of this page).

The wiki page is completely reusable. To use this wiki page for a different animation, all you need to do is copy the source code and then change the address of the ggb file.

For example, http://geogebrawiki.pbworks.com/CarRace  is the SAME page, but now calls the CarRace geogebra file. It took me exactly 30 seconds to make this page from the above page.

Note: The page uses javascript so you must be an administrator to get it to work. (Javascript can be EASILY misused.)

A YouTube video coming soon (hopefully).


COMING SOON (HOPEFULLY): Input boxes that work with Enter in pbworks. (Input boxes are planned for GGB 4.0.) See: http://www.mathcasts.org/mtwiki/InterA/MotionV


B. Tip: Instead of using the movedp.jpg Move drawing pad tool, simply press and hold Shift.Then click and drag.

That is, you do not need to switch tools to zoom and pan. This is great as changing tools can get confusing.

   To zoom, put your mouse pointer at center point of zoom and use your mouse scroll button.

   To pan, press and hold Shift and then click and drag the drawing pad.

   (This works on a PC – feedback for Mac appreciated; http://www.geogebra.org/help/docuen/topics/8.html )

Happy teaching with GeoGebra, Linda

Send me your tips and tricks!



A. Remember Sliders are numbers (that is the object type is a number) that are “showing”.  Here is what the Slider tab for a number looks like.

B. Creating slider t0 = [0,1]  for the bomber.

Creating the slider on the bomber was harder for the following reason.

Here – so that the animation stops when the bomb hits the ground, the plane must fly the start distance minus the INPUTTED bomb distance=d plus the ACTUAL bomb distance=ans. So the total distance we want is totalDistance=start-d+ans. This means the total ACTUAL time is totalDistance/vU  (the velocity in the correct units).

So I defined the slider t0 from [0,1] and then defined t=t0*totalDistance/vU.  

Thus, when t0=0, ACTUAL time t = 0 and when t0=1, ACTUAL time t =totalDistance/vU. This means I can use t in all my calculations in the geogebra file.


Other Credits: Ulven’s animator and Zen Biker Maniac’s, PiMan and MathMagic’s advice. Mike’s and Markus’ endless help. The members of the GeoGebra forum.


Happy teaching with GeoGebra, Linda


Send me your tips and tricks!

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