Two new ideas get introduced once CVC blending is solid. A digraph is two letters making one brand-new sound — "sh" isn't "s" plus "h," it's a single sound with its own symbol. A consonant blend is different: two or three letters that keep their own separate sounds but run together quickly, like the "bl" in "black" (you can still hear both the /b/ and the /l/). Mixing these two up is the most common confusion at this stage.
Why this stage matters
This is where word length jumps — "shop," "chin," and "black" are now readable — and it sets up every digraph a child will meet later (including th, wh, and the vowel teams in Stage 5, which follow the same "two letters, one sound" logic).
How long it usually takes
4–6 weeks for the core digraphs (ch, sh, th, qu) plus ongoing blend practice woven into regular reading.
The most common struggle
Sounding out digraphs letter-by-letter ("s-h-op" instead of "sh-op") — the fix is spotting the digraph as one unit before starting to blend, not adding more phonics rules.