I have given now a couple of talks that involve conformal blocks bundles on the moduli stack $\overline{\mathcal{M}}_{g,n}$, in front of a public of algebraic geometers but not specialists of the field. I have always encountered the same difficulty. The definition itself of bundle of conformal blocks is pretty elaborated and I think that it freightens the audience. 

What can one do to give the flavour of it without killing the talk? Maybe just introduce the parabolic theta functions on the smooth locus and say that the associated bundle degenerates? Or any other brilliant idea coming from physics?