One moment gives several threads, and every child does all of them. Nobody is given a reduced afternoon. What changes is what you expect back, and no child is told which expectation is theirs.
The engine will not let a child be skipped. A moment where somebody has nothing on one of the threads does not render at all.
No age on it, no version of it. Every question is open at both ends, which is what lets one sheet serve a whole family without labelling anybody.
The block under each question is chosen by the engine, not written by hand. A thread says how it is captured and the renderer draws it. Sorting gets boxes, measuring gets a table, a recount gets numbered steps, a museum object gets two columns.
That is why the same engine handles a rock pool, a loaf of bread and a Roman room without anybody rewriting it.
Per child, against that child's own year. Never averaged across them.
Coverage is never averaged. A five year old and a twelve year old are not sixty per cent of the same curriculum between them. That number would look like an answer, which is worse than having none.
And enrichment stays labelled enrichment, however good the afternoon was.