The thesis is the entire speech boiled down into one simple declarative sentence. That sentence should tell your listeners: 1) what your topic is, and 2) what you intend to say about it.
Suppose your topic is "dangerous dogs." Those words should be in the thesis sentence. In fact, they will usually be the subject of the thesis sentence.
Decide exactly what you want to say about "dangerous dogs" and finish the sentence with that.
"Dangerous dogs should not be kept as pets."
"Dangerous dogs can be tamed by training."
"Dogs are dangerous because they have been mistreated."
"Dangerous dogs eat less dog food." (presumably because they get part of their nutrition from those they bite)
Another sample topic: "stronger borders with Mexico." A possible thesis sentences would be:
"Stronger borders (your topic) protect people on both sides (what you intend to say about the topic)."
Then you can explain the thesis with main points like these:
“A stronger border will reduce smuggling.”
“A stronger border will cost you less in taxes and insurance.”
“A stronger border will build a better relationship between the two nations.”
Take another look at the thesis for your up-coming speech. Is it as simple as the sentences shown above. Remember, a simple sentence has no ands, ifs, or buts. It doesn't ask and question, and it doesn't tell people what to do. It just makes a statement that you believe in and are prepared to convince your listeners of through the use of sound support (NETS).
© Frank Richardson, 2009.