Dividing by Zero
It is commonly known that division by zero is not allowed. But why is that so? For starters, look at the function
f(x) = 1/(x  c)
What do you notice about the graph and table as x approaches c?

Related External Resources 
Divide by Zero
A discussion of zero in the denominator of a fraction.
No Matter What Shape Your Fractions are In
A geometric approach to fractions.
Visual Fractions [ java applet ]
A series of java programs using number lines to help visualize fractions and the operations on them.
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