Some other good systematic phonics programs teach one phonogram sound at a time, and teachers who are familiar with these approaches are often surprised to hear that we teach all the sounds from the start.
At Logic of English, however, we are convinced that teaching all the sounds from the start
a) works best,
b) is more efficient and more effective in the long term for developing strong and confident readers, and
c) is not overwhelming as long as you progress at an appropriate pace and provide lots of fun and varied phonogram practice (as Logic of English lessons do!).
Learning all the sounds gives students a complete understanding, from the start, of what a phonogram can say in English words. They can will more about when it can say each sound later on, but they start with the critical piece of information that is going to help them throughout the process.
Why teach all the sounds:
1) First and most simply, because it's true. Teaching all the sounds gives children an accurate picture from the beginning. Even if they don't know yet why or when the phonograms might say their other sounds, if beginning readers encounter words like we, mama, do, go, or all, or if their names have long vowels in them, the spelling of these words will still fit with — and confirm, not contradict — what you have taught them about the language so far.
2) It's more efficient, since students simply learn the phonograms as all of their sounds from the beginning; the sound(s) of a phonogram becomes its verbal "identity," its handle. The letter A is /ă-ā-ä/, end of story. So even if they don't know how this information will be used, it becomes totally automatic for kids that the thing that looks like [a] is /ă-ā-ä/. (You can see a lovely little example of that in this video of Denise teaching some phonograms to a preschooler: https://youtu.be/GmXq5iBtocw). This way, you don't have to come back later and teach additional things to memorize, like "A can also say /ā/. ... A can also say /ä/..."
3) Some children get quite confused or frustrated when they learn the sounds one at a time (or rather when they start learning additional sounds after being told at first that a letter made only one sound). A few examples of this: A few years ago a mom who had recently pulled her discouraged struggling reader out of school and started teaching her Foundations posted on our Facebook page that when she taught her daughter the phonogram a, /ă-ā-ä/, the little girl started jumping around the room in glee, exclaiming triumphantly "I KNEW it! I KNEW it! I KNEW that said more than one sound!" We've also talked to moms who said they had switched from another program to LOE for exactly this reason. With the program, after their children made initial progress with reading and then found out that the letters made OTHER sounds besides the ones they had diligently memorized, they got so frustrated that they began refusing to read! One particular mom reported that her daughter said, "English lied to me."
4) If you teach the sounds separately, children also sometimes begin to conclude (quite reasonably) that there may be any number of additional sounds coming later. They don't know whether or when you've given them the whole story. That can be stressful and overwhelming.
5) In our experience, children generally have no trouble learning multiple sounds of a phonogram, as long as they are practicing the phonograms regularly and learning them at an appropriate pace. In fact, they often learn them faster than the teacher or parent :) It takes less time in the long run to learn all the sounds of each phonogram as a group then to learn all the sounds individually, attaching them to the written phonogram as separate pieces of information.
6) Memorizing a phonogram's sounds as a group, in order of frequency, also gives students an extra resource for reading and spelling: it helps them know which one to try first when sounding out a new word. They don't need to know this early on, but if they've memorized the sounds this way then they can use that when they do learn this concept. More on that in a minute.
How this works in Logic of English curriculum:
1) Learning Phonograms
Phonogram instruction should be paced according to students' mastery, slowing down whenever needed — for kids who struggle or for any child who just needs more time on a concept and skill! The pace should be whatever is comfortable for the students.
But that wouldn't mean teaching one sound at a time; it would just mean taking as many days as are needed to get comfortable with the fact that a says /ă-ā-ä/, that d says /d/, or whatever other phonograms they are working on - not rushing students, but giving plenty of time for fun and playful practice and review.
As a general rule of thumb, I'd say you don't want to introduce a new phonogram until young children are familiar with all the ones they have learned so far and have mastered most of them, because you don't want kids to be overwhelmed. They can move on to a new lesson before all of them are mastered, but they should be comfortable with them and not feeling overwhelmed.
2) Reading with Phonograms
Here is where I think the concern comes in: people assume if you teach all the sounds at once, children have to be able to use all of the sounds at once from the start. This isn't how we do it in Logic of English.
When children are reading, if they come to a phonogram with multiple sounds they can try the first sound first, and then, if it doesn't sound right, try the next sound. We teach the phonograms with the sounds in order of frequency, so the first sound is always the best bet unless there's a particular reason to try another first. Over the course of Foundations children will learn reasons to choose a particular sound first with certain phonograms. The single-letter vowels are one group that has rules letting us know when they can say other sounds.
In Foundations A, children are only going to actually use the first sound of each vowel, the short sound, even though they know all of them. Then, early in Foundations B, they start learning reasons a vowel might say its long sound (at the end of a syllable; a silent E), at which point they start reading words with long vowels in these contexts. It's still fine to try different sounds, but they'll also know what the rules are and know when to look for the possibility that the vowel will say a long sound.
So we aren't asking them to be able to navigate all of the sounds fluently from the start; they know what the sounds are from the beginning, but they'll learn more and more about how to use them as they move through the lessons.
Gradually, they'll also begin working with other phonograms with more than one sound (like CH or OW) and trying their different sounds in words. Most of the phonograms taught in Foundations A and B have only one sound, so the won't have to try out different sounds very often until they are well into the program, but they do get their feet wet and start building fluency with this skill. With practice it becomes completely automatic to try the different sounds of a phonogram when decoding a new word.