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The Google Slides app actually has a unique feature that when you are presenting audience members have the ability to ask questions and have other audience members vote on them. By default, any member in the same domain may ask questions on presentations and you can extend the permissions to others outside your domain as well.
to create a new presentation click New >Google slides > Blank Presentation
from here you will be put into a new presentation. there are a lot of tools and options available to you so feel free to explore and experiment. Here we are only going to cover a few things to get you started with your first prestation.
your first slide should always be a title slide enter in the title of the presentation. To add a new slide click the Plus in the top right or hit the drop down to pick a formatted slide.
When you add a slide, most of them will have premade text boxes that you can start typing in right away. if you want to add a text box click 
in the toolbar, then click anywhere on the slide to create a text box. it can be moved and edit anyway you like within the limits of google text editor. if you want to add a picture click the 
you can upload one from your files or you can use the Search the web option which will open google images on the right side bar. Search your desired image and select image/images that you want then click Insert at the bottom. the images will appear in your currently selected slide and can be resized and moved around to your desired locations on the slide.
if you ever want to start the slide show to see how it looks or present it click Slideshow in the top right next to share and it will full screen you into your presentation. you can navigate the slides with arrow keys or scroll wheel on a mouse. hit Esc on the keyboard to exit.
sharing
if you want to share your presentation with someone so they can see it or even help work on it please click here to learn how to share.
More training
If you want to get more familiar with slides and what it's capable of please click here for googles support page on slides