Yes, these examples use VBA (which is the only way you can get
PowerPoint to respond to whether or not the student has typed the right
answer). There are two things you need to do:
(1) Make sure you unZip the PowerPoint file. The files on my site are
stored as zipped files, and they will not run properly until unZipped
(in Windows XP, you can just drag them out of the zipped folder).
(2) In PowerPoint, make sure that you macro security is set to Medium
(Tools > Options > Security > Macro Security). Then close any files you
have open and reopen them. When it asks if you want to enable macros,
say yes.
--David