Why did the constitutional convention delegates agree on a bicameral legislature

It was a compromise to appease both sides of the debate. They decided to have a bicameral legislature in order to encompass both systems. One that has equal representation regardless of the size of the state, and one system that has representation based on the number of the population. This way both sides would be happy, and that's why today there is the Senate and the House of Representatives, and both houses form the Congress which is the seat of federal power.