I think you may find this assignment useful.  Students should be able to solve each problem without a calculator and really practice their skills with integral exponents, rational exponents and exponent laws in a sequential manner.  I also have a KEY to this assignment here.

In my resources I also have a follow up assignment with variable bases.  I have found that students enjoy working with just rational bases first and then don't freak out as much when they see the variables.

Please let me know if you find this useful...

Colin