How Do You Explain Software Development To 2nd Graders?

First time accepted submitter zimania writes "At the start of every school year, my kids' teachers invariably ask if any parents have any special skills they can present to the students. As a software engineer, I'd like to give a presentation to the classes about developing software. The tricky part is making a presentation fun, inspirational, and easy enough for 2nd and 4th graders to grasp. Has anybody been brave enough to attempted such a thing? Are there kid-tested prepackaged presentations freely available? Would it be best to present the development of a simple game? Web page? Any advice is welcome."