ALEKS & Total Probability

[LaterBloomer]

Hi, does anyone know of a location where I can get a good (read: SIMPLE) explanation of the law of total probability? It's a concept in an ALEKS stats course that I'm taking, and I'm not getting it. I've searched the web, the khanacademy site, and looked in both Complete Idiot's Guide to Statistics and Statistics Workbook for Dummies, but the search, like my understanding of this concept, is coming up blank. I've printed up the dictionary definition in ALEKS. My suspicioun is that if my grasp of the other probabilty laws was better, I'd understand this concept more readily, but it isn't, and I don't.

Thank you. banghead