I'm trying to get a basic understanding of the big bang in order to teach an advanced oceanography course to high school students this summer. The course starts with one lecture on the origins of the universe, solar system, the earth, and the ocean. I think I get the basics of BBT from quark soup onward. I'm wondering if there is an explanation for where the quark soup came from? Was it created during inflation? I typically see diagrams of the evolution of the universe that list inflation as a precursor to quark soup. My understanding is that the universe has, and continues to expand from what once was a singularity. I realize that what goes on in a 'singularity' is probably beyond what we will ever be able to know. And as far as I understand, it is still an open question as to why the universe began expanding in the first place, why it continues to expand and why that expansion rate looks like it has changed over time. (I know we believe that dark energy is involved but it seems that we still have a lot to learn here.) I understand (vaguely) that matter can be converted into energy and vice verse, and I'm under the impression that the earliest universe was energy dominated (or perhaps only energy?) and then later through interactions like this http://ns.umich.edu/new/releases/8167 matter was created? If the earliest universe was energy dominated, was there a reason for this? (Can only energy exist when things are too hot or too dense? Or perhaps in theory only energy can exist in a singularity since there is no space for matter to occupy?) Was the initial inflationary expansion of the universe necessary for the creation of matter (if matter did not already exist)? Beyond this, I think I vaguely understand that as the quark lepton soup cooled, quarks 'combined' to form a proton/neutron plasma. Then after more cooling, hydrogen atoms formed (and some helium and other simple atoms) and at this time light was allowed to travel freely (CMB). Other heavier elements did not form because the universe expanded/cooled too quickly? Over time gravity clumped matter into regions (clusters, galaxies, stars) of high density again and nucleosynthesis occurred to create heavier elements in stars and supernovae. Things continue to evolve into the universe we know today... I have a bachelors degree in physics, but it has been a while since I've studied quantum or cosmology and ultimately I'd like to be able to teach this to high schoolers. I'd appreciate any insight this forum can offer!