What is a Thesis Statement?

ESTABLISHING A THESIS STATEMENT
A thesis first establishes the topic of your essay. Example topics:

• The hunting of wolves in the Arctic
• College entrance exams
• Hybrid automobiles

Remember,these are not thesis statements, they are topics.
ADDING ARGUMENT
In order to create a thesis, you have to add an opinion, or point of view that is arguable or open to interpretation to your topic. 
Examples:

• The hunting of wolves in the Arctic should be stopped because of the danger of the wolf's extinction.
• College entrance exams are not the best way to test a student's readiness for university study.

• Hybrid automobiles, while more environmentally friendly than traditional cars, still have serious environmental impacts because of manufacturing techniques. 

The parts not underlined show the writer's opinion about the underlined topic.