Many use hyperlinks to direct people to information such as websites by highlighting text. In PowerPoint you can add links to shapes by creating an invisible hyperlink.
This can be done by drawing a shape, selecting it and then finding the Action Button (2003 version will find it under Slideshow; later versions will find it under Insert). You then select which slide you want to link to the shape. Think of it as the first slide as the main page and the other slides are hidden behind it. This process adds more interactivity to PowerPoint and is a useful tool for Interactive White Boards.
There are many ways to use this process:
Create a Non-Linear slide: Create a Mindmap or picture and link the slides, rather than sequential
Create a Quiz or Game: You can create a quiz for students or they could make their own. Create a multiple choice and when the students select the correct answer they see a picture and sound.
Choose your own adventure: Add interest to story writing by asking students to write different alternatives to their story, the reader can choose the different options.
Create an Interactive Map: Take a screenshot of a map, add a shape and place it on the map. Link the shape to a slide with information about the place.
Create Flash cards: when learning words or another language. Make a box with a word and link it to a slide with a matching picture. Make a box with Japanese script and link it to the sound.
This process can really be adapted to suit any subject area