For teaching resources and learning aids pertaining to effect sizes and the analysis of statistical power, check out MadMethods’ new series of e-books:

“The primary product of a research inquiry is one or more measures of effect size, not p values.”
~ Jacob Cohen

How to manuals

“Statistical significance is the least interesting thing about the results. You should describe the results in terms of measures of magnitude – not just, does a treatment affect people, but how much does it affect them.”
~ Gene Glass