For which exam are you studying?

If it's developer or dba, you can practise your 2008R2 skills on a 2012 machine.

Just ignore all the new stuff 🙂

If it's BI, it will be a bit more trickier as SSIS has changed a lot, and SSAS has gotten an extra development model. However, if you stick to SSAS multidimensional, it's almost exactly the same as in 2008R2.