This may be too early in the year for you guys to talk intelligently about the determinants of economic growth since we have not studied any Macroeconomics, but you can take a stab at it anyway:
On his blog, Economist Tyler Cowen summarizes a debate about whether the strong economic growth that Ireland has been experiencing is due to its "youth dependency ratio" being low. This means that there are less children per each working adult (therefore, there are less children that must be supported). Dr. Cowen explains the reasons why the youth dependency ratio might have an effect on economic growth here.
Also, here is the original article by Malcolm Gladwell in the New Yorker that started the debate, which might give a less techincal explanation and may be a better place to start..
(Source: Marginal Revolution)