University of Saskatchewan (Canada)
University of Saskatchewan: Moderate Exercises on Exponents
Site provides two sets of problems about exponents and exponential functions which are moderately difficult. Site provides hints for the problems and solutions with explanations for students.
University of Saskatchewan (Canada)
University of Saskatchewan: Advanced Problems on Exponents
Site provides five sets of advanced exponential function problems, along with hints and solutions to the problems. A good challenge at the advanced level for students.