1. Heart
   Lungs
2. Skin
   Sternum

While the heart, lungs and skin are all organs in the human body, the sternum is a bone. It is also called the breastbone, and it protects your heart while holding your ribs in place.

1. Water
   Hydrogen
2. The atomic sign for oxygen
   The number of vibrations it takes to boil water

H2O represents a water molecule made of two parts hydrogen and one part oxygen. By the time you leave high school, you should know that water is essential to the existence of life on Earth.

1. Harper Lee
   William Shakespeare
2. Charles Dickens
   Leonardo DiCaprio

Several works by Shakespeare have landed on the high school reading canon. Though many of them are his more approachable works, students still have a difficult time wrapping their brains around the play with the speech that is common in Shakespeare's works.

1. X can't equal 4
   X = 8
2. X = 4
   X = 1/4

If 2x = 8, you can divide both sides of the equation by two and see that 1x = 4, or x = 4. Basic algebra like this helps high school students move forward to more difficult calculus.

1. Badger
   Hamster
2. Raccoon
   Dog

When an animal is nocturnal, it means that they do most of their eating, mating and hunting at night. These animals tend to have larger eyes that help them see in the dark. Dogs aren't considered nocturnal.

1. "Who's" should be "whose."
   "Who's" should be "who is."
2. "Dog" should be "dogs."
   There is nothing wrong with this sentence.

"Who's" is a contraction of the words "who" and "is" or "who" and "has," while the word "whose" shows possession. When we ask who the dog belongs to, we are showing that someone has possession of the dog.

1. Mercury
   Venus
2. Earth
   Jupiter

While Mercury is the closest planet to the sun, the hottest planet in our solar system is Venus. Venus has a dense atmosphere that holds all of the heat from the sun. Temperatures on Venus have been recorded at 870 degrees Fahrenheit.

1. It travels at the same speed in both.
   Air
2. Water
   Sound always travels at the same rate.

Though you hear differently when you're underwater, sound does travel faster when it is in water. This is because the particles in water are closer together, allowing vibrations of sound to travel faster.

1. 9
   18
2. 81
   3

When you take a number and multiply it by itself, you have squared that number. The number itself is known as the square root. Think of it as the base for the square. So, three multiplied by three is nine, meaning the square root of nine is three.

1. The Pythagorean Theorem
   The Quadratic Formula
2. The Hyperfinder
   Triangle Formula

The Pythagorean Theorem was designed to help people figure out the sides of a right triangle (a triangle that has a 90-degree angle). The letters "a" and "b" represent the sides of the triangle, and "c" always represents the hypotenuse (the side opposite of the right angle).

1. Around 750
   Just over 200
2. Under 50
   Around 100

While human infants have around 300 bones in their bodies, eventually, many of these bones fuse together. Human adults are then left with around 206 bones in their bodies, each of them with a specific purpose and function.

1. A side character or villain of a story
   A triangle with two right angles
2. A main character or hero of a story
   A circle with a large circumference

The majority of the stories you see have protagonists and antagonists, especially in high school. Though many stories these days attempt to blur the lines between the two types of characters, the stories we read in high school have a clear separation between the two.

1. Nothing changes.
   It decreases.
2. Space only affects weight, not height.
   It increases.

If you spend time in zero gravity or in space, you will get taller. This is because while on Earth, the disks in your back are compressed under your weight due to gravity. In space, these disks expand, giving you a little room to grow.

1. Mercury
   Iron
2. Gold
   Lead

Mercury is the only metal that remains in its liquid form at room temperature. As a matter of fact, mercury doesn't reach its solid form until about -38 degrees Fahrenheit, which is pretty cold.

1. Washington, D.C.
   Cincinnati
2. Versailles
   Paris

Paris is home to several great museums that house the world's finest art. Among those museums, you will find the Louvre, which has made cameos in several movies. It's the museum with the giant glass pyramid.

1. Mercury
   Neptune
2. Uranus
   Jupiter

The majority of the Greek gods have Roman names as well. Each god had attributes and ruled over specific things. Poseidon (or Neptune) was the god of the sea, and he was often visualized with a trident.

1. Barcelona
   Toledo
2. Madrid
   Granada

While many believe that Barcelona is the capital of Spain, it is about half the size of Spain's actual capital, Madrid. Madrid is located in a centralized area of the country and is completely landlocked.

1. About 5,000 years
   About 500 years
2. About 5 million years
   About 5 billion years

Given the research and calculations of the leading scientists in the world, it is estimated that the sun is approximately 4.6 billion years old. This means that it is in the middle of its life cycle as a star.

1. Trees
   Humans
2. Ants
   Turtles

While turtles can live over 100 years, scientists have found trees that have been alive for thousands of years, making it through several great natural disasters and earth-changing events.

1. Depicting the passage of time
   Hyperrealism
2. Unusual visual angles
   Visible brush strokes

Impressionism does work toward accurate lighting and the changing qualities of light, but it does not focus on hyperrealism. The fact that viewers can see the brush strokes alone tells us that impressionism doesn't work toward hiding the medium.

1. Annually
   Bi-annually
2. Every four years
   Every two years

The reason the Olympics are held every four years is that's how often they were held in Ancient Greece. The "Olympiad" was a four-year span of time that the Greeks used instead of years.

1. About 745 days
   34 days
2. 34 hours
   Under 10 hours

Jupiter is the largest planet in our solar system, but it is also the fastest rotating planet. Because it is a gas planet, Jupiter rotates faster around the equator, but only a few minutes faster each rotation.

1. Mom
   Makes
2. Dinner
   For

Verbs are action words; they describe what something is doing or being. In this sentence, the verb is "makes," and it shows that the mother is creating something (or putting something together), which is dinner in this case.

1. After "walks"
   Before "the"
2. After "she"
   This sentence doesn't need a comma.

Not every sentence needs a comma. While most people like to put commas just about everywhere, there are only specific cases where they are necessary. They are definitely used to separate the items in a list or before conjunctions that link two independent clauses.

1. F. Scott Fitzgerald
   John Fitzgerald Kennedy
2. J.D. Salinger
   Marco Carpio

"The Great Gatsby" has long been considered the great American novel. It follows a recent college graduate through interesting encounters in fictional villages on New York's Long Island.

1. Ulna
   Radius
2. Circumference
   Diameter

The diameter of a circle is the line that goes straight through the middle and touches both edges. The circumference of the circle is the distance around the circle and the radius goes from the center to the edge.

1. Red
   Orange
2. Yellow
   Green

Green is the beginning of the cold colors on the color wheel. Warm colors generally can be associated with heat, fire and warm environments. It is rare to see only cold or warm colors in any given work of art, but it is not unheard of.

1. Iron pyrite
   Real gold
2. Gold and copper
   Copper

Fool's gold is definitely not made out of gold. You can tell that it isn't regular gold because it forms in cube shapes. It may look like the most unnatural thing you've ever seen, but these cubic crystals can be found throughout the United States.

1. Beethoven
   Tchaikovsky
2. Milner
   Handel

Those of you who took music history, music theory or band classes know that Tchaikovsky was one of the most famous composers from the romantic period. Even if you don't know what he's done, chances are you've heard his work.

1. Double negative
   Double she
2. Comma splice
   There is no error in this sentence.

A comma splice occurs when a comma is used to separate two independent clauses (or two complete sentences). There are two ways to fix this error. You can replace the comma with a semi-colon or with a period.

1. Iris
   Albien
2. Lens
   Pupil

The pupil itself is actually a hole that is located in the center of the iris. It expands and retracts to allow light into the eye so it can strike the retina. It is black because all of the light is absorbed in it.

1. In the center of the bone
   Surrounding the bone
2. In the skin
   In red blood cells

Bone marrow is the substance in the center of bones. It's also where blood cells are produced and contains two different types of stem cells. It is one of the most important substances in a human's body.

1. Ribonucleic acid
   Deoxyribonucleic acid
2. Don't Never Answer
   Derna Nucleo Acrid

Deoxyribonucleic acid (DNA) is created by two chains that wrap around each other. This is called a double helix. DNA is found in every living organism on earth. It helps scientists solve mysteries dating back millennia.

1. A dog
   A frog
2. A giant bug
   A princess

Kafka's "The Metamorphosis" has been studied for decades in literature and language arts courses across the country. It is a story of the human condition and what happens when we wake up to considerable change.

1. Spain
   Germany
2. Russia
   The United States of America

While other countries do encounter tornado activity, the United States faces far more. This is because the winds from both the Gulf of Mexico and the Rocky Mountains make the perfect conditions for funnel clouds and turbulent weather.