Each of the words in this spelling list follow the spelling rule I and O may say long I and long O when followed by two consonants. This rule is found in many systematic phonics programs.
LD, NT, MB also may be short as in gild, mint, glint, and limb.
LL, MB, and TH also may be short and broad sounds as in doll, bomb, tomb, womb, cloth, and moth.
At Logic of English, we have concluded that the spelling rule "I and O may say long I and long O before two consonants" is still the best way to teach this principle. However, it it still helpful to teach students the most common places this occurs.