You're welcome GEBS.... and that advice could also influence your longer, in person presentation. If I have to get 20 pages in before I see some tangible, actionable results, it is not going to work. Put your cards on the table first, then tell me a story.
We all are tempted to make similar mistakes. I recently had to give a presentation to Hartmut Esslinger, the founder of frog, and 40 of his design students who flew in from Vienna. I was crafting a presentation of case studies of recent public work. The VP of the creative group globally a happened to be in the studio from NY the day before and I gave him a run down of what I was planning... he said to me "Michael, that is a beautiful presentation, but you won't get three slides in" Instead he advised me the same as I advised you above, show them what I have done, hit them over the head with that, and then romance a story.
So I backed up to a Pecha Kucha I gave about my work and my approach at a RISD event earlier in the year and used that as a base, starting with a slide that has 130 tiles of projects from the past 15 years! It is an attention getter, puts the cards on the table as I suggested earlier... It went well.
You can see the base presentation here: 3MB PDF... I modified this so it wasn't this exactly, and had more frog work in it obviously. I also ended the presentation by showing a book on Hartmut and frog that I had bought the year after I graduated design school, 1999, when most of these kids were 10 years old. It was a nice prop to put things into perspective for them.... plus I got the book signed http://michaelditullo.com/articles/MD_PK.pdf