What it is. A subject and its verb have to match in number.
Why our test works. Agreement errors are almost always caused by a phrase sitting between the subject and the verb — *the box of apples ARE*. Asking one-or-many about the SUBJECT, not the nearest noun, is the fix, and it is a check the child can run alone.
Leans on. Lessons 11 and 18.
Watch for. Have them cross out the phrase between subject and verb. The error disappears when the distractor does.
Read and use Mud Learns to Agree from Sentence Island, pp.109–113. The worked example is the one you build on the board: Teacher reads the key passage of Mud Learns to Agree aloud with the book open and models t The class reads Writing Book 4, p.62 — our own page, so a child who was absent can still get the lesson.
You open by saying where this sits — what it follows and what it is part of — in one sentence, and then you give them the reason it matters, in your own words, for about ten seconds. Before anything new, sixty seconds of retrieval on U9 set 2: ask, take the answers from boards rather than hands so you see all thirty, and do not re-teach — note who has lost it and carry on.
Then you do one yourself, building it on the board and leaving it up: Teacher reads the key passage of Mud Learns to Agree aloud with the book open and models the move it teaches on one sentence. The board copy is what they look back at when they stall, so it stays there for the whole lesson.
The We-do is the main whiteboard moment of the lesson — short answers, boards up on your signal, every child visible at once. Class applies the move from Mud Learns to Agree to two sentences together, checking against the book's own example. If the answer is a whole sentence rather than a word, take it on their notebooks instead, because a sentence written on a whiteboard is written once and destroyed.
They open Writing Book 4 to page 62 and read it with you. Stop at the worked example and let them look at it.
Exit directions in full, standing still, before anyone moves. Then they work alone: In your notebook: apply Mud Learns to Agree to three sentences of your own, double-spaced.
You close on the exit direction — Read out one sentence that uses Mud Learns to Agree. — taken from every child before anyone stands, and then the line you want them to still have tomorrow: The parts must agree with each other.
Have them cross out the phrase between subject and verb. The error disappears when the distractor does.