18 July 2014, 03:36 PM ET
18 July 2014, 03:34 PM ET
Estrogens are hormones that that are important for sexual and reproductive development, mainly in women. They are also referred to as female sex hormones.
18 July 2014, 03:09 PM ET
Osteoarthritis, the most common form of arthritis, occurs when cartilage between the joints wears down over time.
27 June 2014, 11:54 AM ET
Squirrels are nimble, bushy-tailed rodents found all over the world. There are more than 200 species of squirrels.
26 June 2014, 06:19 PM ET
Newton’s Third Law of Motion states, “For every action, there is an equal and opposite reaction.”
26 June 2014, 06:14 PM ET
Newton’s Second Law of Motion states, “The force acting on an object is equal to the mass of that object times its acceleration.”
26 June 2014, 06:08 PM ET
Newton’s First Law of Motion states, “A body at rest will remain at rest, and a body in motion will remain in motion unless it is acted upon by an external force.”
26 June 2014, 06:04 PM ET
Newton's laws of motion formalize the description of the motion of massive bodies and how they interact.
26 June 2014, 03:34 PM ET
Mice are small rodents with pointed noses, furry round bodies, large ears and long, often hairless, tails. There are hundreds of species of mice.
25 June 2014, 02:34 PM ET
Crocodiles are large reptiles that belong to the order Crocodilia, which includes alligators, caimans and gharials.
24 June 2014, 09:18 PM ET
Matter is the “stuff” of the universe. There are five known phases, or states, of matter: solids, liquids, gases, plasma and Bose-Einstein condensates.
24 June 2014, 01:42 PM ET
Mustangs were first brought over to the Americas by Spanish explorers.
23 June 2014, 06:26 PM ET
Medical marijuana is legal in some states, but debate rages on about whether the health benefits outweigh the risks.
23 June 2014, 05:35 PM ET
Marijuana produces a range of psychological and physical effects that can be unpredictable at times.
21 June 2014, 12:13 AM ET
The Mongolian Death Worm is said to be a large creature with spikes and acidic spit.
20 June 2014, 03:37 PM ET
There are more than 3,000 species of snakes in the world and there is at least one type of snake on every continent except Antarctica.
19 June 2014, 11:20 PM ET
Jaguars are large cats that can be found in North, Central and South America. They are identified by their yellow or orange coats, dark spots and short legs.
12 June 2014, 01:38 AM ET
Kinetic energy is the energy of mass in motion. The kinetic energy of an object is the energy it has because of its motion.
11 June 2014, 12:23 AM ET
A proof is a rigorous argument that shows a mathematical claim to be true. Arguments that are proven become theorems, such as the Pythagorean Theorem.
11 June 2014, 12:05 AM ET
“Earth science” is a broad term that encompasses four main branches of study — geology, meteorology, oceanography and astronomy — each of which is further broken down into more specialized fields.
10 June 2014, 10:41 PM ET
Hamsters are small rodents that are commonly kept as house pets.
09 June 2014, 08:07 PM ET
Wolves are large carnivores — the largest member of the dog, or Canid, family. Wolves are common to all parts of the Northern Hemisphere.
06 June 2014, 02:58 AM ET
The Vandals were a “barbarian” Germanic people who sacked Rome. The name has become a synonym for destruction.
05 June 2014, 05:56 PM ET
Rabbits are small mammals with fluffy, short tails, whiskers and distinctive long ears. There are about 30 species of rabbits around the world.
05 June 2014, 03:02 AM ET
Removing a tick correctly can lessen the chance of contracting a tick-borne illness.
03 June 2014, 02:52 PM ET
Camels are mammals with long legs, a big-lipped snout and a humped back. There are two types of camels: dromedary camels, which have one hump, and Bactrian camels, which have two humps.
31 May 2014, 03:39 AM ET
Transistors are tiny switches that can be triggered by electric signals. They are the basic building blocks of microchips.
31 May 2014, 03:23 AM ET
In many ways, the history of civilization is the history of chemistry. Humans have always sought to identify, use and change the materials in our environment.
31 May 2014, 02:25 AM ET
About 40 million Americans suffer from seasonal allergies. The most common culprit is pollen.
30 May 2014, 01:18 AM ET
Chemistry is the study of matter, its properties, how and why substances combine or separate to form other substances, and how substances interact with energy.
29 May 2014, 11:12 AM ET
Manhattanhenge, a phenomenon when the setting sun is perfectly aligned with Manhattan's grid-patterned streets, occurs twice a year with a full sunset, and twice a year with a half sunset.
29 May 2014, 03:03 AM ET
Nikola Tesla is often called one of history’s most important inventors, one whose discoveries in the field of electricity were way ahead of his time.