The Web site of Catholic Charities USA offers a wide variety of useful resources related to social justice for catechists and teachers:
Scripture references on the principles of Catholic Social Teaching
Quotes from key church documents on Catholic Social Teaching
An explanation of the seven principles of Catholic social teaching
Prayer Resources : a compilation (fairly extensive) of prayers submitted by agencies across the Catholic Charities network.
Relexions: One for the Advent season and several on the theme of "Mission and Poverty"
Articles on the Catholic Charities USA Code of Ethics