Why did the framers of the constitution create the legislative branch with bicameral structure

The framers create a bicameral structure because different states wanted different methods of representation i.e. population or 2 per each state.

As a compromise they created a bicameral structure where the Senate represents each state with two representatives and the House of Representatives which represents based on population.

map scale refers to the relationship (or ratio) between distance on a map and the corresponding distance on the ground. for example, on a 1: 100000 scale map, 1cm on the map equals 1km on the ground.