A great site with activities, quizzes, videos and even karaoke about every area of the science curriculum. Very useful when introducing new topics.
http://ictmagic.wikispaces.com/Science
This is a resource-rich site, with a math, language and comprehensive science content. Slideshows, videos and comprehension quizzes have made this a site I will use often.
94%? Do they use it to do their homework, or while they do their homework? There is a huge rift between how adults and students use technology largely because of why they use technology. While I use Twitter to find a great resource for a digital citizenship project, one of my students might use it to find the party at Brian Halloway's house.
Scholastic posts "daily starters" for review and practice in language arts and math skills. Teachers can select grade levels and even reveal answers. New skills and activities are posted every day!