Khan Academy
Khan Academy: Q&a: Neuron Depolarization, Hyperpolarization, & Action Potentials
Khan Academy answers a question about hyperpolarization and depolarization with a written explanation and links to helpful videos.
CK-12 Foundation
Ck 12: Life Science: Excretion
[Free Registration/Login may be required to access all resource tools.] You might have noticed that sometimes your urine is darker than usual. This can happens when your body is low on water and trying to reduce the amount of water lost...
University of Arizona
University of Arizona: Blood Types Tutorial
This site from the University of Arizona describes how blood type is passed on from parent to child. The tutorial covers the genetics of the ABO blood groups as well as Rh factor. There are even practice problems and blood type calculators!
Annenberg Foundation
Annenberg Learner: The Habitable Planet: Unit 9: Biodiversity Decline
This is an extensive learning module on biodiversity and its decline. It looks at ways biodiversity is threatened, the possibility of another mass extinction, the causes and consequences of habitat loss, factors that drive biodiversity...
Soft Schools
Soft Schools: Animal Structure, Function, and Behavior Quiz
Take an interactive quiz over animal structure, function, and behavior. After completing the quiz, check your score, and then revisit any incorrect question for further review.
Soft Schools
Soft Schools: Food Nutrition Quiz
Take this interactive, multiple-choice quiz over food nutrition, then review your score and any missed questions at the end.
Soft Schools
Soft Schools: Biodiversity Quiz (Ecological Problems)
Take an interactive quiz over ecological problems affecting the environment. After completing the quiz, check your score, and then revisit any incorrect question for further review.
Khan Academy
Khan Academy: Science: Health and Medicine
We have some from here but I can't tell how many as they may have video embed codes. I did find some we don't have, as well as some we do have among the embedded videos. There is also a Youtube channel at...
Library of Congress
Loc: Everyday Mysteries: What Is the Strongest Muscle?
There are a variety of ways one can look at what might be the strongest muscle in the body. This site defines the various types of muscles and goes on to explain which would be considered the strongest.