US Environmental Protection Agency
Epa: Making a Natural P H Indicator
At this site you will find a step by step process for making a natural pH indicator. One of the main materials you need to have on hand is a red cabbage.
CK-12 Foundation
Ck 12: Physical Science for Middle School
This digital textbook covers core physical science concepts and includes interactive features, real world examples, and videos.
Khan Academy
Khan Academy: Water Autoionization and Kw
Learn about the autoionization of water, the autoionization constant Kw, and the relationship between [H+] and [OH-] in aqueous solutions.
University of Arizona
University of Arizona: Biochemistry
Problem sets, tutorials, and activities related to biochemistry.
Other
Chemical Reax/exothermic Reactions
A wonderfully complete primer on exothermic reactions in the context of chemical spills. Covers Reactions with Air or Water, Combustible Organics, Polymerization Reax, Decomposition, Corrosion, and much much more.
Science is Fun
University of Wisconsin: Home Experiments
This resource presents a collection of simple science experiments kids can do using household materials. The procedures include diagrams and are simple to follow.