Powerpoint, or Keynote, or Google Slides are used by many speakers. Used well they can be a really useful tool. Used badly they can kill a presentation stone dead!
It is worth summarizing what you are saying – and this is especially helpful for people who don’t speak the same language as you. But be careful not to put too much of what you’re saying on the slides – people came to listen to you, not read your script with you.
Don’t put too many words on a slide – less is more. Trying to limit your points to 3 or four words, not whole sentences. Maybe use a picture instead of words.
When you begin and end chapters or sections of your talk, use a slide to summarise what you’re going to say or have just said. This helps non-native speakers keep up. It also helps you focus.
As a rough guide, each slide is worth about 2 minutes of talk. This does NOT mean that if you write 10 slides, you have a 20 minute talk – it means that if you prepare a talk, and build a presentation, and then see that you have, say 17 slides, you are probably going to speak for about 30 minutes – so you should definitely try out your talk and check the timing before you go in front of the audience.
To illustrate what we mean, take a look at this Powerpoint advice section converted into two slide shows – one bad, one good. Which one would you rather sit through?