Every day I assist people with their presentations and I’m often asked how many slides they should have. The answer to this question is simple….as many as it takes. It might be necessary to linger on a slide for a while or rapidly progress your slides to keep up with your verbal content. Given that there should only be one key message per slide, you should use as many slides as necessary to visually support your speech.
Slides should be illustrating or reinforcing the point that you are making, and should therefore be relevant to what you are saying. Imagine a newsreader telling an audience about bush fires. The newsreader would be supported by an image on the screen behind their shoulder relating to the fires. If the next story relates to stock market prices, it would be confusing for the audience to be viewing an image of bush fires while they’re talking about shares. The same principle applies to your presentations.
It comes back to the very first principle of presentation design…content comes before slides. Once you have your key messages identified and incorporated into a well-crafted speech, you are then in a position to think about what slides should reinforce your message.