I could scour the web and find thousands of awesome ways to use manipulatives in my classroom. Using them makes math really hit home. So what do you do when you don't have a certain manipulative, but you know if you could just put your hands on more geo boards or base ten blocks you'd have a more successful lesson. Along comes the National Library of Virtual Manipulatives by the Utah State University. I think that hands-on is of course better, but it never hurts to have some virtual manipulatives bookmarked---especially if your school is short on money for extra supplies.