[Free Registration/Login may be required to access all resource tools.] Definition of an endothermic reaction, the role of energy, and examples of endothermic reactions.

[Free Registration/Login may be required to access all resource tools.] Explores how enzymes work and their role in chemical reactions in living cells.

[Free Registration/Login may be required to access all resource tools.] Explains what a combustion engine is, its purpose, and how it works.

[Free Registration/Login may be required to access all resource tools.] Explores what gamma rays are and their sources, and the dangers and uses of gamma rays.

[Free Registration/Login may be required to access all resource tools.] Discusses properties of gases, why they exert pressure, and atmospheric pressure.

[Free Registration/Login may be required to access all resource tools.] Kinetic theory of matter and how kinetic energy relates to the state of matter.

[Free Registration/Login may be required to access all resource tools.] Properties of liquid matter.

[Free Registration/Login may be required to access all resource tools.] Mendeleev's periodic table and the groups and periods.

[Free Registration/Login may be required to access all resource tools.] Metalloids and their properties.

[Free Registration/Login may be required to access all resource tools.] Metals and their properties.

[Free Registration/Login may be required to access all resource tools.] Definition of covalent compound, how they are named and how they differ from ionic compounds.

[Free Registration/Login may be required to access all resource tools.] Definition of technology and how technology evolves.

[Free Registration/Login may be required to access all resource tools.] Definition of nucleic acids and their structure and function.

[Free Registration/Login may be required to access all resource tools.] Definition of pH and the strength of acids and bases. How to use the pH scale and why pH is important to living things.

[Free Registration/Login may be required to access all resource tools.] Machines and friction, the efficiency of a machine and how to calculate it.

[Free Registration/Login may be required to access all resource tools.] What a radioisotope is and why they have unstable nuclei. Elements in which all of the isotopes are radioactive.

[Free Registration/Login may be required to access all resource tools.] What a solenoid is and how to change the strength of its magnetic field, and some uses of solenoids.

[Free Registration/Login may be required to access all resource tools.] What exactly is a fish? You probably think the answer is obvious. You may say that a fish is an animal that swims in the ocean or a lake, using fins. But not all...

[Free Registration/Login may be required to access all resource tools.] The job of the eye is to focus light. The parts of the eye help it to carry out its job. Follow the path of light through the eye as you read about it. Learn more...

[Free Registration/Login may be required to access all resource tools.] Did you know that you see the largest organ in your body every day? You wash it, dry it, cover it up to stay warm, and uncover it to cool off. Yes, your skin is your...

[Free Registration/Login may be required to access all resource tools.] Definition of heat and how thermal energy is transferred.

[Free Registration/Login may be required to access all resource tools.] Definition of work and how it relates to force and distance.

[Free Registration/Login may be required to access all resource tools.] There is an amazingly wide variety of birds. Birds are vertebrates. Almost all have forelimbs modified as wings, but not all birds can fly. Learn more about birds in...

[Free Registration/Login may be required to access all resource tools.] Did you know that blood is a tissue? Blood is a fluid connective tissue that is made up of red blood cells, white blood cells, platelets, and plasma. Learn more...