This may be a bit late, but better late than never. If you check out the August 29 post of Aplia Econ Blog, you will find some interesting resources for your discussions on economic growth.
First, you'll find a link to a podcast interview with Paul Romer. Romer is one of the founders of the Aplia site, and is well-known in economic circles for his work on economic growth theory. You will also find a link to Romer's entry on "Economic Growth" from The Concise Encylopedia of Economics. While the podcast is long for classroom use, you may want to listen to it and use parts for purposes of discussion. Or you may want to absorb the material yourself on background, and then develop your own lesson.
However, I would also encourage you to pick up David Warsh's book, Knowledge and the Wealth of Nations. Warsh goes into the history of growth theory and how Romer developed his insights. One of the more interesting insights to me was the idea of knowledge spillovers, and how knowledge that allows for a change in productivity, spreads and benefits the larger economy, allowing for improving growth rates that are referenced in the podcast and article. While this may seem like a lot of time to spend on a topic, the potential return in "increased growth" in your students' understanding can make it worthwhile.
I look forward to your comments and ideas.