Mathematical
games can foster mathematical communication as students explain
and justify their moves to one another. In addition, games can motivate
students and engage them in thinking about and applying concepts
and skills.
The following links to an updated version of the eexample.

Playing Fraction Track (5.1.1)
In this twoplayer eexample, students take timed turns
racing to the end of each fraction line by moving one or more of their markers
to sum to a given fraction value. Options include a pass and restart button.

The original applet below conforms more closely to the pointers in the book.