how do i determine what generation my ipod touch is

Your iPod will have a model number that is about 8 characters etched on the back. You can also connect the iPod to iTunes to figure out the model. Then lookup the model number and it should come up as a generation. Knowing the year it was bought or manufactured helps. A site known as everymac has all the specs of the device and when it was made along with advantages and disadvantages of the model.