There are a few things to be aware of before using the Photo Slideshow Add-on. First, it will randomly crop some images to fit into slides. Second, some images that were captured in landscape mode will be shown in portrait mode. Third, to make your slideshow automatically play in a webpage you will need to make sure that you have enabled "auto play" as illustrated in my screenshot below.
The Photo Slideshow Add-on for Google Slides could be useful in creating a slideshow to showcase the highlights from a school event like a field trip, play, or athletic event. You can make the slideshow a collaborative effort by having people add images to a shared Google Drive or a shared Google Photos album. In doing it that way you avoid having to give everyone access to edit the slideshow.
Learn more about Google Slides in G Suite for Teachers.