ccna

hi friends,

while attending a ccna class i had doubt that if a switch or a NIC card is a layer 2 device and can recognise only mac-addresses, how can it accept an ip address.. when I asked this question, my faculty promptly turned down by just replying it as a stupid question.. I still dont have an answer for my question whether it is stupid or not.. can anyone come forward to help me out?

rgds
sudarsan