SOS Classroom is a project started and directed by the Writing Program at the University of Southern California. The project was started in response to the shut-down of summer school programs in Southern California and around the United States.

SOS Classroom is a compilation of K-8 resources that can be used in the classroom and or be used by students independently. The resources on SOS Classroom have been listed at the suggestion of teachers and parents. All resources are tagged and placed into one of seven categories sorted by subject and grade level. The categories are mathematics (K-2, 3-5, 6-8), language arts (K-2, 3-5, 6-8), and ESL.

Applications for Education
SOS Classroom could be a good place to start your search for elementary and middle school resources.

Here are some related resources that may be of interest to you:
Learning Beyond the Classroom
Picturing the Century – Lesson Plans and Worksheets
A Great Collection of K-8 Math Resources