As requested by the teacher, I have modified my existing Primary School Speed simulation to show the radomized graph.  
The student will need to try to guess the variable being represented on the Graph. Enjoy!

/htdocs/ntnujava/ejsuser/130498/users/sgeducation/engrg1/2013Speed/PriMathSpeedV9_pkg/PriMathSpeedV9.propertiesFull screen applet or Problem viewing java?Add http://www.phy.ntnu.edu.tw/ to exception site list
Press the Alt key and the left mouse button to drag the applet off the browser and onto the desktop. This work is licensed under a Creative Commons Attribution 2.5 Taiwan License
Download EJS jar file(1028.7kB):double click downloaded file to run it. (6 times by 6 users) , Download EJS source View EJS source