I learned to read and write when I was almost three. My parent's house was, and still is, a mini library, as is mine. I taught all of my children to read before the teachers with their inefficient, new fangled ideas got hold of them, and my children are teaching my grand children in the same way.
Language is a code, we have to crack it, the only way is by knowing the key, the key is the alphabet and the sounds are far more important than the names, a b c, not Ay, Bee, Cee. I don't hold with rote learning; however, singing the alphabet sounds does wonders for learning to read and write, as does the singing of multiplication tables for learning maths.
Listen intently to your children read, make special time for it, and always remember, children love to please and always want to get it right, so don't be afraid to tell them when they are wrong as long as you teach them what is right.