Our lab researches Tetrodotoxin, which is a neurotoxin found in newts (type of salamander) and most famously in puffer fish. Garter snakes in certain locations have evolved resistance to this toxin and there is a predator-prey arms race between the two species. I could present this research (which goes back 20 years). I work on novel predation on newts as well as a species of flatworm that produces this toxin as well. With novel predation, we observed otters eating newts, which ended up having really low levels of the toxin.
I feel that the research done in our lab is really ecologically relevant, and easy to condense for an 8-12 year old. I would love to get some audience participation throughout the presentation to really get the kids involved and thinking. Also, I would be able/willing to bring some animals for them to see/hold. I would likely be able to bring garter snakes, newts, and possibly other amphibians/snakes if you thought that would be appropriate.
For more information about the Faraday Event, go to http://starhousediscovery.org/faraday.html.