The central idea and everything in the paragraph should relate to and develop that idea. Every sentence should fit with the others. Whenever your flow of ideas shifts, provide transitions.
Transitions connect distinct ideas.
They can indicate that one idea expands, exemplifies, qualifies, summarizes, implies, or results from another. They can contrast, compare, show relationships. Modeling has long been used to teach dance, sports, and crafts, as well as skills in subjects such as home economics and chemistry. Modeling can also be applied deliberately in the classroom to teach mental skills and to broaden horizons. There references usually consist of repeated words or pronouns inserted into the subject position.