oar
An oar is used to row a boat.
oatmeal
Oatmeal is a cereal.
Barack Obama is the 44th President of the USA.
obelisk
An obelisk is a tall, four-sided tower topped with a pyramid.
The oboe is a woodwind instrument with a double reed.
observatory
An observatory is place where people observe the skies, using a device like a telescope.
An obtuse angle is greater than ninety degrees.
An ocean is a large body of salt water that surrounds a continent. Oceans cover more the two-thirds of the Earth's surface.
Oceania is a region of islands in the Pacific Ocean, including the Salomon Islands, Micronesia, Kiribati, Fiji, Tonga, Polynesia, Samoa, Australia, and others.
Ocelots are wild cats from rainforests and grasslands in the Americas.
An octagon is an eight-sided figure. Stop signs are octagons.
An octahedron is an eight-sided geometric solid.
October is the tenth month of the year.
The octopus is an ocean animal (a cephalopod) that has eight arms and lives on the sea floor. The plural of octopus is octopuses.
odd number
An odd number is not divisible by two.
ogre
Ogres are ugly, scary and make-believe.
Ohio is a state in the United States of America. Its capital is Columbus.
oil
Oil is a greasy liquid.
oilcan
An oilcan is a container for oil.
oil painting
An oil painting is a picture made using oil paints.
The okapi is a nocturnal, giraffe-like mammal from African rainforests.
Oklahoma is a state in the United States of America. Its capital is Oklahoma City.
old
When someone or something is old, it has been around for a long, long time.
The old English sheepdog is an affectionate, long-haired dog that was originally bred in Great Britain.
An olive is an oily fruit that grows on an evergreen tree.
The Olympic Games began over 2700 years ago in ancient Greece.
omelet
An omelet is a dish made from eggs.
An omnivore is an animal that eats plants and meat. People are omnivores
on
The vase is on the table.
One is a small number.
one half
When something is divided into two equal parts, each of these two parts is one half of the original object.
onion
Onions are sharp tasting vegetables.
Something that is open is not shut. The door is open.
The Virginia opossum is the only marsupial from North America.
Opposites are things that are very, very different from each other. Some examples of opposites are: left and right, big and small, up and down, tall and short.
Orange is a color. You can mix red and yellow paint to get orange.
Oranges are sweet, juicy fruit.
orange juice
Orange juice is made from oranges.
Orangutans are large, tree-dwelling apes from rainforests in southeast Asia.
orb
A ball-shaped object is an orb.
The Moon orbits the Earth. The Earth orbits the Sun.
orb weaver
The orb weaver is a type of spider that builds a loosely-woven web.
Orcas are also known as killer whales. An orca eats hundreds of pounds of fish and marine mammals every day.
orchid
Orchids are colorful flowers that live in warm areas.
ordinal number
An ordinal numbers show the position in a series or the order. Some ordinals are first (1st), second (2nd), third (3rd), fourth (4th), fifth (5th), sixth (6th), seventh (7th), eighth (8th), ninth (9th), tenth (10th), eleventh (11th), twelfth (12th), etc.
Oregon is a state in the northwestern United States of America. Its capital is Salem.
Origami is the art of folding paper into beautiful shapes.
The oriole is a black and orange bird that eats fruit and nectar. It builds a hanging nest.
Ornithomimus was an ostrich-like dinosaur.
The crested oropendola is a tropical black bird that makes long, pendulous nests.
Oryx are long-horned antelopes from dry areas in Africa and Asia.
The ostrich is the largest bird and is from Africa. It can't fly, but it runs very fast.
An otter is a playful aquatic mammal.
ouch
Sometimes, when they're hurt, people say, "Ouch."
ounce
An ounce is a unit of weight. One cup of water weighs eight ounces.
our
This is our beachball; we share it.
Ouranosaurus was a sail-backed, plant-eating dinosaur.
He is going out the door.
outlet
An electrical outlet is a device that is connected to an electrical supply. We plug electrical devices into an outlet so they can receive power. Outlets are usually mounted on a wall.
outside
When you are outside, you are not in a building or other structure.
An oval is an egg-shaped figure.
Ovens get very hot. You can bake food in an oven.
An oven mitt protects your hand when you put things in or out of an oven.
The cloud is over the mountain.
overalls
Overalls are baggy pants with shoulder straps and a piece of fabric covering the chest.
overcoat
An overcoat will keep you warm when it is cold.
Oviraptor was a small, omnivorous dinosaur.
Owls are birds of prey that have large eyes and very good eyesight. Most owls hunt at night.
Oxen are large, hairy mammals that live in the far north.
The oyster is a soft-bodied marine animal that is protected by two hard shells.