The Slide Finder feature allows you to search for slides when you are in a slide show. ProTools for PowerPoint adds a new menu item in your menu when you right-click on the slide show:

Clicking the Slide Finder menu item brings up the dialog box that allows you to search for slides in the presentation:

Type the words that you wish to find in the Search box and click the Search button. In the Search Results box, you will be presented with the slides that meet the search words. You can click on the items in the search results to see a thumbnail view of the slide.

Slide Finder searches for words in the text boxes, shapes, grouped-shapes, tables, graphs and diagrams on the slides.