Teaching A People's History is a wonderful site that a History or English teacher could use to enhance their lesson plans on a given topic.  Teaching A People's History has detailed lesson plans in PDF format for a wide range of topics and time periods that will push students of all abilities to critically analyze a given topic deeper and in meaningful ways that are not always apparent.  One unit I looked at was on the Potato Famine that decimated Ireland.  After presenting the facts and extended reading, it asked students to start to think about what were some of the problems that led to such a preventable disaster.  At the end of the unit it laid blame not just on the English landlords but the farmers as well as the church.  If you would like to learn more about the Howard Zinn Project of Teaching A People's History, please read the Frequently Asked Questions.