the early period in human history when people made tools and weapons only out of stone
Stone Age
someone who lived in a cave in the early stages of the development of human society
cavemen
the action of planting trees, vegetable or fruits
farming
the period of time during which work began to be done more by machines in factories than by hand at home
Industrial revolution
a country without a king or queen, usually governed by elected representatives of the people and a president
Republic
a group of countries ruled by a single person, government, or country
empire
one of the seven large land masses on the earth's surface, surrounded, or mainly surrounded, by sea and usually consisting of various countries
continent
the activity of buying and selling, or exchanging, goods and/or services between people or countries
trade
Being not in danger or at risk
safety
