What we need to think about is how much kids are ready for in terms of making the connections between letters and the sounds they make, and then blending those sounds together, listening as they do so to make sure they are making a word, and adjusting as necessary. This is a pretty complicated process. Children do not just suddenly learn it.
Let me illustrate with a small story about my son. You probably have your own version of this story. When he first started talking, he pronounced 'milk' as 'mmm.' After a while, he would say something that sounded like 'miw.' Still later it was 'meeyoo.' He was pretty excited when he got the ending sound and he said it a lot for a while: 'miyuk' with a lot of emphasis on the /k/. Nowadays it sounds almost like 'milk' but the /l/ is still a little tricky. This has been MONTHS of approximation.
Reading and writing happen the same way. Children start out wherever they start out and gradually over time make their way closer and closer to the target.
So back to sounding it out. Here is an abbreviated set of steps children generally take as they move toward learning how to sound words out. But please remember that sounding words out without also thinking about meaning is not reading!
Also, knowing all the letters and/or their sounds is not a prerequisite for these things. That often happens alongside these steps.
Your child might...
- recognize some letters in what they are reading (they may also recognize some whole words, but that's a different conversation)
- memorize books or parts of books, then be able to actually point to some of the words they are saying (like repeated refrains or parts in a different typeface)
- use the beginning of a word to try to predict what the word will be (we call this predicting and not guessing because guessing implies that children are not using any information. When they predict, they use the fist sound of the word, and also their knowledge of what would make sense based what's going on in the book). Instead of saying, "Sound it out," try to prompt children to do this by saying, "get your mouth ready." This is the very beginning of sounding it out.
- Somewhere in here, children get pretty good at decoding simple words that have a consonant-vowel-consonant pattern (CVC words in the trade). Dog and cat are two good examples of these. The short vowel sounds are sort of the easiest vowel sounds to deal with early on. Instead of saying SIO with these words, try, "Put the sounds together."
- The next thing children might be able to do is look for familiar groups of letters that make a predictable sound. These are called onsets and rimes, but many teachers call them chunks. sp- and -ent are chunks. We don't sound out the letters separately. Instead we take them in almost as a single sound. Early on, children may know a small number of these chunks. They can make the sound of the chunk accurately, and try to predict the rest of the word. For instance if the word is together, children might first see to as a familiar chunk, and then try to predict the rest based on context. Instead of SIO, try, "Do you see any chunks you recognize?"
- As they learn more of these chunks they get better and better at putting them together to figure out words.
- The next stuff they start to learn is how different letter combinations affect vowel sounds. This is REALLY confusing, and takes a long time to figure out. Kids may recognize that a silent e makes an earlier vowel long (as in hike), but have no idea that a single consonant after the vowel in a multisyllabic word (as in hiking) also makes the vowel long. This is partly because it is more complicated, and partly because it is not as consistent a rule. Most CVC words have a short vowel, but many CVCe words do not have a long vowel. Have and love are common counterexamples to the rule. Instead if SIO, try, "remember how the vowel sounds when x is happening in the word," or something like that.
- So the more kids read, the more words they learn, the more new words they can learn by comparing them to their growing repertoire of memorized words. When they start reading books similar to Henry and Mudge, or thereabouts, they are able to do what we mean when we say, "sound it out." Except that we don't say that anymore. Instead of SIO, try "You know all these chunks because you've seen them in other words. First let's look at them all separately, then you can put them together to figure out the word."
- During every one of these stages, "what would make sense here?" is also a really great prompt. It reminds children to hold onto meaning even as they are focusing on letters and sounds."
This is a pretty short primer on early reading, but it should get you started, and arm you with some less frustrating ways to help your child through. And just so you know, all these steps typically happen over a 3 year period. So let your child spend a long time getting good at each thing. Remember, they get better at reading by reading a lot. They get better at reading by reading books that FEEL EASY, and they want to keep reading when they feel GOOD AT IT.
Let me know how it goes!