Writing Systems of the World 6, Exercise 1: how the Greeks added vowels

Phoenician was an abjad: 22 consonant letters, no vowels. Greek had vowel
sounds that needed writing and had no matching letters, so the Greeks
reassigned five Phoenician letters (Greek alphabet article):

aleph -> Alpha  /a/
he    -> Epsilon /e/
yod   -> Iota   /i/
ayin  -> Omicron /o/
waw   -> Upsilon /u/

The result is a script where vowels have independent letterforms, which the
Alphabet article calls the defining step of the true alphabet in the narrow
sense. The reader no longer has to infer the vowels.