Bread-Bakers v103.n020.12

I was really just interestd in the answer to the question.  My niece is
using yeast in a science experiment and this question came up. I said too
much will make the bread rise too much, others says it makes it fall. I
think we are argueing symantics. I think it falls after the dough rises too
much because it gets too heavy or explodes.  Help. Any thoughts.