Spelling patterns: When two vowels go walking...
A phonics rule learned by children goes like this:
When two vowels go walking, the first does the talking, and it says its own name. You can hear it sung here.
This teaches us how to pronounce the following vowel combinations: bait, laid, braid, pail, sail, main, pain, rain, and train. (All have the long a sound -- i is silent).
Caution: there are exceptions. Said goes against the rule and rhymes with bed.
We can also use this rule to help us pronounce heat, beat, real, and feat. It also helps with vowel combos beginning with o, like goat, boat, and coal.
The rule is less helpful with vowel combos that begin with i and u, which are often diphthongs -- combination vowel sounds. In other words, with diphthongs both vowels do the talking. Examples of words with diphthongs include dial, riot, trial, suet, and cruet. (All of these diphthong words have two syllables.)
To spell English correctly means we need to pronounce words correctly first. To learn more about English vowel sounds, listen to Teacher Joe on You Tube as he lists and pronounces the 15 sounds of American English.