1. volcano
   sun
2. moon
   asteroid

Scientists believe that an asteroid impact caused the extinction of the dinosaurs. This is believed to have happened roughly 65 million years ago.

1. Pluto
   The galaxy
2. Asteroids
   Gravity

Ocean tides are caused by gravity - specifically, the moon's gravity. Without gravity, there would be no tides... or people for that matter.

1. 5%
   25%
2. 70%
   100%

Water covers around 70% of the Earth’s surface. It is essential for all life.

1. ears
   voices
2. instruments
   vibrations

Sound is made from vibrations. Vibrations create sound waves.

1. True
2. False

This is false. There are many good bacteria that you need, to stay healthy and survive.

1. 186
   1,860
2. 18,600
   186,000

Light travels around 186,000 miles per second in a vacuum. That's pretty fast!

1. plantivores
   eativores
2. foodivores
   herbivores

Animals that eat only plants are herbivores. Humans are omnivores, meaning they eat plants and animals.

1. antiemitics
   antivirals
2. antibiotics
   antidepressants

Bacterial infections are treated with antibiotics. Bacteria are one-celled organisms.

1. Deep
   Down
2. Under
   Mariana

The Mariana Trench is the deepest known point in the world’s oceans. The Mariana Trench is in the Pacific Ocean.

1. True
2. False

This is False. Jupiter has several moons, the largest of which are Europa, Ganymede, Callisto and Io.

1. dog
   cat
2. monkey
   sheep

Dolly the sheep was the first mammal to be cloned. Dolly was cloned in 1996.

1. 1
   2
2. 3
   4

Hydrogen has an atomic number of 1. It is the first element of the Periodic Table.

1. True
2. False

This is true. Venus spins backward relative to the other planets.

1. Solid
   Liquid
2. Gas
   All of the above.

Water can be a solid, liquid or gas. Solid water is called ice, of course.

1. Atlantic
   Pacific
2. Indian
   Arctic

The largest ocean on Earth is the Pacific. The Atlantic is the second largest ocean.

1. lizardologist
   paleontologist
2. godzillaologist
   psychologist

Someone who studies dinosaurs is known as a paleontologist. Dinosaurs roamed the earth until about 65 million years ago.

1. water
   oxygen
2. boron
   helium

Sound travels faster in water than in air. About four times faster.

1. Mars
   M & M
2. Kit Kat
   Milky Way

Earth is in the Milky Way galaxy. The Milky Way looks like a flattened spiral.

1. rock
   fruit
2. seed
   fungus

Mushrooms are a type of fungus. So are mold and yeast.

1. viruses
   plagues
2. big
   small

Colds are viruses. They cannot be treated with antibiotics.

1. Darwin
   of England
2. The first
   Lindbergh

Charles Darwin developed the idea of natural selection. This is also known as survival of the fittest.

1. Venus
   Mars
2. Earth
   Pluto

Venus is the hottest planet in the solar system. The planet's average surface temp is about 460 degrees Celsius.

1. slug
   sloth
2. turtle
   cheetah

The fastest land animal in the world is the cheetah.

1. photosynthesis
   diet
2. eating
   sleeping

The process that involves plants using energy from sunlight is called photosynthesis. Plants convert carbon dioxide into food.

1. Oxygen
   Helium
2. Hydrogen
   Carbon dioxide

Humans breathe out carbon dioxide. Its chemical formula is CO2.

1. amber
   coal
2. diamonds
   oil

Fossilized tree resin is called amber. Amber sometimes traps bugs and plants as it hardens.

1. United Kingdom
   Australian Ocean
2. Bali Islands
   United States

The United States has more tornadoes than any other country in the world. We get about 1,200 of them a year.

1. Halley's
   Malley's
2. Galley's
   Bailey's

Halley’s Comet was last seen in the inner Solar System in 1986. Catch it again in 2061.

1. Missouri
   Minnesota
2. Amazon
   Rio

The longest river in the U.S. is the Missouri River. The Missouri is slightly longer than the Mississippi River.

1. Helium
   Hydrogen
2. Boron
   Silica

Water is made up of two elements, hydrogen and oxygen. Water has two hydrogen atoms and one oxygen atom.

1. eels
   elephants
2. cats
   dogs

The largest land mammals on Earth are elephants. There are two types of elephants - Asian and African.

1. Helium
   Carbon
2. Oxygen
   Boron

Helium is the gas used in balloons that float. Helium floats because it is lighter than air.

1. big green
   tyrannosaurus rex
2. slimy frog
   fearfully great lizard

The word dinosaur comes from a Greek word for "fearfully great lizard."

1. True
2. False

This is false. Jupiter, Uranus and Neptune also have rings.

1. The Great Barrier Reef
   Mt. Vesuvius
2. The Rocky Mountains
   Lake Huron

The largest living structure on Earth is the Great Barrier Reef. It is located in Australia.