A strong speech is centered around a clear claim. Your claim should be arguable and not just state the topic of your speech. Some differences between the topics and claims are as follows:
A TOPIC:
- is a phrase
- is thematic
- has no bias
A CLAIM:
- is a simple declarative sentence
- states a position on a public controversy
- is spoken by someone to someone about something important they have in common
For more information on the difference between topics and claims, please see this video.