Long vowels are pronounced the same as the name of the vowel. If you know how to say the alphabet properly, or at least the vowels, you can use this. A as in father is pronounced ahh, so it is short. A as in apron is pronounced like the name of the letter A so it is long. Easil sounds like an E, Ice sounds like an I. Ostrich sounds like Not, as opposed to Note which sounds like an O. Boy is a tough one because of the Y. If we replace the Y with a T, we have Bot pronounced like Robot or Not with a short O. This O sound is different than in Boy. If we replace the T with a TE, we have Bote (not a word), like Note with a long O. The O sound of Bote is closer to Boy than Bot is. So I would say Boy is also a long O.