The 2012 general election is the first to use new districts redrawn following the results of the 2010 U.S. Census. That means many voters will be voting at a different polling place this year.
Fortunately, you can check on-line to find out where you need to go to vote. The Iowa Secretary of State's Office maintains a website link that allows you to enter your home address and learn which voting precinct you live in. You can find it at: https://sos.iowa.gov/elections/voterreg/pollingplace/search.aspx