Under Common Core, 8th grade math is 8th grade math :-) It has bits and pieces of all math areas- but it looks very similar to previous course outlines for "Pre-Algebra"
http://www.corestandards.org/Math/Content/8/introduction/

A very accelerated group would be Algebra 1 in 8th grade.

If you're super bored, you can read all the Common Core math acceleration, compaction and standards- http://www.corestandards.org/assets/CCSSI_Mathematics_Appendix_A.pdf