As a computer teacher I am often met by a classroom teacher dropping her kids off for class by a statement similar to,"We are studying Rocks and Mnerals, so anything you can do in that area would be great!" as she turns slowly and walks away. So, now I keep all of the on-line lessons I have created for just such an emergency you can use them too by clicking here
I am also listing a few places I use when I need to find and use an instand lesson Web Currents
Where do you find things you need fast?