A main cause of the trade was the colonies that European countries were starting to develop. In America, for instance, which was a colony of England, there was a demand for many labourers for the sugar, tobacco and cotton plantations. Paid labourers were too expensive, and the indigenous people had largely been wiped out by disease and conflict, so the colonisers turned to Africa to provide cheap labour in the form of slaves.
Work hard so everyone will succeed
He does not support the annexation of the Philippines. ... He means if the Filipinos begin to read the constitution and declaration, they'll figure out the United States had contradicted their statements regarding their liberty and independence.
One reason factory owners employed children because they were significantly cheaper than hiring an adult. "the child is paired one shilling or one shilling and six pence". This shows that it's more cost efficient to hire a child.
Another reason factory owners employed children because of their size. Here is a quote to support this "The smallest child in the factories were scavengers they go under the machine". This shows that if the child is smaller they can do more dangerous jobs than an adult.