The purpose of this activity is to experience what it's like to use a web page with screen reader software.
Go to WebAim's Screen Reader Simulation. Start the simulation and try to do its three tasks.
WebAIM (an organization at Utah State University) has created several good simulations of accessibility problems.
Another way to get this experience is to use an actual screen reader. JAWS and Window Eyes both have time-limited trial versions that you can install to see what screen reading is like.