I start with examples of evaluating log expressions that don't require a calculator, then compare that with a problem that does require the change of base formula. Here are my other PreCalculus lessons involving Logarithms Check out , there you will find my lessons organized by class/subject and then by topics within each class. Find free review test, useful notes and more at If you'd like to make a donation to support my efforts look for the "Tip the Teacher" button on my channel's homepage