SOLUTION: y=1 if x is rational and y=0 if x irrational. how would you describe this on a graph.

In a coordinate plane, draw two straight lines y= 0  and  y= 1.


Take a needle.   // If you don't know what a needle is, consult a dictionary.


Using the needle, make a hole in each point (x,1) on the line y= 1, where x is irrational.


In other words, using the needle, remove each point (x,1) on the line y= 1, where x is irrational.


    It is infinitely long job, if you do not use other special tools - but you are a patient person, isn't it :).


When you complete this job, you will get the requested graph.