A persuasive speech seeks to change the audience's beliefs about a particular topic or issue.
The best keyword for the charities persuasive speech will be the charity name, such as The Humane Society of America, Fisher House Foundation, The Leukemia and Lymphoma Society, etc. Look at the assignment instruction also to help you build or determine what type of information is needed for your designated charity. That type of information can also be a keyword search term.