In order to write a persuasive essay focusing on three ways that Jonas changes throughout the novel The Giver, you may want to organize your thoughts into a thesis statement by presenting an argument that you will discuss for the remainder of your essay. The following is a good example of a thesis statement that focuses on three ways that Jonas changes throughout the novel:

"When Jonas becomes the community's Receiver of Memory, he gains perspective on his society, rebels against the world's restrictive social institutions, and develops sympathy for the naive citizens living in his community, which motivates him to alter the community for the better."

This thesis statement introduces the three ways that Jonas changes, and one can elaborate on the experiences that lead to Jonas's increased perspective. Some of these experiences include his memory of sled riding, which leads to a conversation regarding Sameness and climate control. Jonas also learns about love, family, and war during his sessions with the Giver. After Jonas discovers that "release" is simply a euphemism for death, he rebels against his society by refusing to remain in the community. Despite his initial negative feelings, Jonas sympathizes with the ignorant, naive citizens and wishes to alter his community for the better. He also demonstrates sympathy for Gabriel by saving him and traveling to Elsewhere with the innocent infant boy.

You need to focus by tying these three ideas together thematically.  Write a thesis where you relate how Jonas changes to the theme.  For example, Jonas changes as he realizes the truth about his world.  A theme might be that differences should be celebrated and not stifled.