This model was devised by Atkinson and Shiffron and outlines the three permanent structures of memory to be the sensory register, short-term and long term memory. Each of these structures differ in their coding, capacity and duration. For example the short term memory arrives from the sensory register in its raw form but then is encoded in several ways such as visually, acoustically and semantically. You can use Baddeley's study to support this information.