Listen to how Chimamanda Adichie makes her speech powerful and engging by telling many anecdotes. Her standpoint being the danger of a single story leads to stereotyping and predjudice.
Listen to how Malala makes her speech powerful by using images and repetition.
Listen to how Martin Luther King, Jr. makes his speech powerful by using imagery (giving us pictures) and repetition.
Listen to how Steve Jobs uses anecdotes from his life to make a powerful point.
There's no single formula for a great talk, but there is a secret ingredient that all the best ones have in common. TED curator Chris Anderson shares this secret -- along with four ways to make it work