UCCP Online: Algebra 1
Online course for Algebra 1. Each section contains short video examples for each concept.

National Library of Virtual Manipulatives
Online manipulatives for all areas of math.

Grammar Girl
Quick and dirty tips for better writing.

Biology

UCCP Online: Biology
Online course for Biology. Each section contains short video examples for each concept.

UCCP Online: Biology Web Lab
College Prep Biology Web Labs

Earth Science

Physical Science

Library of Congress
Digital Collections and American Memory Project.