Two ideas that are easy to mix up. 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. Blends need no new sound — every letter in "stop" is already known — but saying two consonants back to back is a new step, so the stage opens with two blend lessons (blends at the start of a word: frog, clap; at the end: milk, jump) before the first digraph. Until then, the plan and its printables keep words with blends out of reading practice.
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
3–6 weeks: two consonant-blend lessons, then the core digraphs (qu, ch, sh, th, ng, nk), with blends reused in reading from then on.
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.