Here's why:
* Short "i" sounds are typically represented by the letter "i" followed by a consonant. In "did," the "i" is followed by the consonant "d."
* Long "i" sounds are usually represented by the letter "i" followed by a vowel or a silent "e" at the end of a word.
Therefore, the "i" in "did" makes the short "i" sound, like the "i" in "pig" or "tin."