The 18 Electron Guideline: A Primer
This consists of two parts (and a solution, which is linked below under "Related Resources", but for which you will need a faculty privileges): a primer for students (best if handed out prior to class so that students can read it beforehand, or delivered in pre-lecture format) and a worksheet. The worksheet is designed to be done in small groups with assistance from an instructor. In very large classes, in which the instructor cannot circle amongst the groups, the instructor can work through each example after the groups have a few minutes to work the problem on their own.