In order to create a simple mnemonic to remember the 12 Olympian gods of the ancient Greek pantheon, it is helpful to group the names into like categories. For example, there are 5 deities that start with "A," 2 deities with "D," 4 deities with "H" and the two loners, Poseidon and Zeus.
The advantage of a mnemonic learning device is that, by grouping together like objects, the overall number of objects to remember is reduced. In the above example, grouping the deities whose names start with the same letters reduces the number of the group from 12 to 5. When a student memorizes each group separately, the entire task is broken down into more manageable fragments.
The 12 Olympian gods of the Greek pantheon, known as the Dodekatheon, are Aphrodite, Apollo, Ares, Artemis, Athena, Demeter, Dionysus, Hephaestus, Hera, Hermes, Poseidon and Zeus. Often included in the group are the deities Hades and Hestia, neither of which is commonly considered an Olympian god. Hades was said to dwell in the underworld rather than on Mount Olympus with the other deities. Hestia and Dionysus are often swapped in lists of the dozen. Other, lesser Olympian gods were minions of the primary pantheon.