English has 18 vowels. Or maybe 17. Or maybe some other number. Let’s pick a number that seems nice, such as 18, and do the best we can with that number.
Some of these vowels are short and unproblematic. They are called the “lax” vowels. Let’s say these:
|a||æ||cat, lamb, has|
|e||e||get, debt, well|
|i||ɪ||ill, jim, kick|
|o||ɒ||hot, what, moll|
|u||ʌ||hull, dumb, pup|
|oo||ʊ||book, put, could|
There are 5 vowels, ‘a,’ ‘e,’ ‘i,’ ‘o,’ ‘u,’ but there’s also a 6th, ‘oo,’ which turns out to be useful. I’ve put the IPA in the table, but it doesn’t really help, as there are 6 different symbols for 6 different sounds, so if you don’t know them, you learn nothing. Maybe later they will come in handy or something. The problem now is that we’ve used up all the vowels letters (and we cheated by using ‘oo’ as well), and we still have 12 sounds left to spell. This means we need to use context in some way.