How to Upgrade iMac Hard Drive (2009, 2010, 2011): EveryMac.com
My 12 y/o son is so excited. Found him a pristine Mid-2010 27" iMac for $100. Going to give it the SSD upgrade but he's stoked to start recording music with it :
Apple iMac Mid 2010 27" Hard Drive + SSD Upgrade Dual Drives - YouTube