Explaining "how to" requires students to research a subject, evaluate what's important, and create a guide for someone else to follow. It gives them an opportunity to write for an authentic audience and purpose and use skills that rank very high on Bloom's taxonomy. When we ask students to summarize without giving them an audience and purpose all we are doing is asking them to "guess what the teacher thinks is important."

A few weeks ago I posted on the great opportunities for students to teach others by creating how to videos. Since then I 've found a great source list of How To video sites at ReadWriteWeb.