I had seven children. They all learned to read before kindergarten. The earliest was 18 months. I taught them the sounds of the letters first. Then I taught them words that started with each letter. It becomes easy to connect sounds and form more words. I made up silly songs about everything including their names in the songs as well as the things they liked to do. I made tape recordings and played them as they were engaged in any activities. This was background to normal play. They would listen and sing along, memorizing the sounds and the words. It was very stimulating. (It was fun.)
Everything that has letters and words on it became a reading lesson. Every sign, every food package, etc. Words are everywhere. I bought index cards and printed the name of everything in their rooms and stuck them on with a piece of masking tape. For example: It did not take more than a minute to know that b-e-d is bed. Linking a word with a tangible thing makes reading come to life. As soon as the word was learned the sign was removed. The game was to make all the signs disappear as soon as possible. However the signs would remain as long as necessary. There was no pressure, just enthusiasm. It really works.
Of course I always read to my children. When you read to kids, you should not be boring. Make the characters real. Use your voice to sound like the animal or character you are reading about. Read with feelings and emotions. Make the book come to life. It’s amazing how reading skills will take off, when you make it real.
My child who was reading at 18 months progressed to Irish fairy tales and medical books for kindergarten. She was hungry for books and words and knowledge. The others became avid readers too of geography and culture, history, novels.and how-to books.
You may use similar techniques for mathematics. I made up silly songs to teach basic math and the times tables. The children knew their basics and times tables as kindergartners. It’s all about listening, reading, relating and remembering. If your children can read well and comprehend what they read; the whole world is their oyster. Children learn more and faster in the early years than at any other time in their lives. (Make the most of it.)