http://nlvm.usu.edu/en/nav/frames_asid_191_g_3_t_1.html
http://pbskids.org/cyberchase/games/functions/functions.html
http://shodor.org/interactivate/activities/FunctionMachine/
http://www.amblesideprimary.com/ambleweb/mentalmaths/functionmachines.html
http://www.quizville.com/numberMachine2.php
http://www.mathplayground.com/FunctionMachine.html
http://www.crickweb.co.uk/assets/resources/flash.php?&file=fmach
http://mathematics.hellam.net/functions2.html
http://www.bbc.co.uk/schools/ks2bitesize/maths/number/number_patterns/play.shtml
