[Free Registration/Login may be required to access all resource tools.] Discusses what a magnetic field reversal is and the evidence that this has happened with the Earth.

[Free Registration/Login may be required to access all resource tools.] The mouth and stomach are just two of the organs of the digestive system. Other digestive system organs are the esophagus, small intestine, and large intestine....

[Free Registration/Login may be required to access all resource tools.] Some of the most important animal behaviors involve mating. Mating is the pairing of an adult male and female to produce young. Adults that are most successful at...

[Free Registration/Login may be required to access all resource tools.] Definition of cellular respiration and its overall chemical equation. The energy changes that occur during cellular respiration, including in photosynthesis.

[Free Registration/Login may be required to access all resource tools.] What optics are and different types, and how they work and form images.

[Free Registration/Login may be required to access all resource tools.] Do you ever wonder why some birds are big like ostriches and some birds are small like robins? Or why a lion has a mane while a leopard has spots? In the 19th...

[Free Registration/Login may be required to access all resource tools.] Ways that waves can interact with matter and examples.

[Free Registration/Login may be required to access all resource tools.] Definition of chemical change and examples, signs of chemical change and how it can be reversed.

[Free Registration/Login may be required to access all resource tools.] Imagine you open a gallon of milk, and you suddenly smell a foul odor. Your sense of smell has informed you that the milk has spoiled. So you pour the spoiled milk...

[Free Registration/Login may be required to access all resource tools.] A Punnett square is a special tool derived from the laws of probability. It is used to predict the offspring from a cross, or mating between two parents. Learn more...

[Free Registration/Login may be required to access all resource tools.] Many animal behaviors are ways that animals act naturally. They are not learned behaviors. Cats are natural-born hunters. They don't need to learn how to hunt....

[Free Registration/Login may be required to access all resource tools.] Many animal behaviors change in a regular way. They go through cycles. Some cycles of behavior repeat each year. Other cycles of behavior repeat every day. Learn...

[Free Registration/Login may be required to access all resource tools.] What the speed of sound is and its variation in different media, and the effect of temperature on the speed of sound.

[Free Registration/Login may be required to access all resource tools.] Orbital motion and why it occurs, and the orbits of the Earth around the sun and the moon around the Earth.

[Free Registration/Login may be required to access all resource tools.] Describes the fronts that occur when two air masses collide.

[Free Registration/Login may be required to access all resource tools.] Radio waves and how they are used for AM and FM radio and television.

[Free Registration/Login may be required to access all resource tools.] Ecology is the study of how living organisms interact with each other and with their environment. Organisms interact with each other through various mechanisms, one...

[Free Registration/Login may be required to access all resource tools.] Reflection and how it produces an image, regular and diffuse reflection and the law of reflection.

[Free Registration/Login may be required to access all resource tools.] Describes electromagnetic devices and how they work.

[Free Registration/Login may be required to access all resource tools.] Definition of gravity and how it relates to weight. Includes a video. [3:54]

A module that uses pictures, videos, reading passages, and review question to go over what a magnet and magnetic pole are, and how magnetic force is related to magnetic field. This site may require free registration to access all...

[Free Registration/Login may be required to access all resource tools.] Atoms and how they are related to elements, and the particles that make up atoms.

[Free Registration/Login may be required to access all resource tools.] It might sound good to you to have a condition where you feel no pain. But actually this type of condition would be very dangerous. What would happen if you strained...

[Free Registration/Login may be required to access all resource tools.] Covers seafloor spreading and the mechanism for continental drift.