Software to produce an interactive presentation?
Here are two ideas that might meet your needs:


Codingbat allows you to create a teacher account and your own problem sets.  You have to put in test values for all of your functions, but you can see the results that your students produce.
A worksheet.  "Now that we've covered that idea, go ahead and see what you can do with number 4 on your sheet."


Since you're just trying to make your lesson interactive, a low-tech approach might be your best approach.  Providing a work-along worksheet allows you to focus your time and energy on other parts of the lesson when you prepare.

Best of luck!