Main idea and Controlling idea

 While writing an essay one of the most important parts is the topic sentence. This is comprised of a main idea and a controlling idea. 

An example of a topic sentence is, "Horses are the most interesting creatures in the Caribbean".  The main idea is "Horses" and the controlling idea is that they are the most interesting creatures in the Caribbean. 

This information relayed in this class wasn't difficult to understand and I learnt that the main idea doesn't always have to be the first word in the topic.