This interesting site provides photographs, letters, newspaper articles, quotes, and famous speeches all related to the life of Gandhi. While the text is probably best suited to middle and high school students, younger students could use other parts of the site to learn about Gandhi for biography projects or studies of passive resistance.
This is one of the most active sites I have checked out. I think it has a little bit of everything for everyone. It has information on just about any topic one would want to check out. It has beginning of the year activities. It has helpful worksheets and ideas for things from social studies to English to science. It is a great site to check out. If it has an activity for one grade there is probably a way to adapt to another or from topic to topic as well.
An excellent resource for students researching the Holocaust. Probably more useful for the high school student who wants transcripts/interviews/actual documents from world leaders who were involved in policy decisions during this time. PBS, a reliable trusted resource.
National Center for Education Statistics Dare to Compare allows students to check what they know about subjects (social studies, math, science) compared with other US and international students from a 600+ question database. The "Create A Graph" page is a useful interactive tool for teaching ways to communicate statistics.