Useful outcome: Check equal membership before skip counting; repair the actual grouping or count account.
Prepare: Twelve marks in boxes containing 2,2,3,1,2,2; thirty-two marks with the same local three/one defect; twenty-four marks and a faulty twos list for twenty.
Notice · 3 minutes
Show the alleged pairs. Ask whether boxes that look alike necessarily hold the same amount. Invite the child to count members of any chosen box. The teacher names the claim “each has two”, not its correctness.
Model · 5 minutes
In the twelve-mark model, one box has 3 and another 1. Move/direct one mark from the three-box to the one-box. Now six pairs remain 12 objects. Merely changing a label cannot make an unequal group equal. A count list assuming 2 for every group was unsupported before repair.
Guided attempt · 8 minutes
Organise twenty-four as twelve pairs. Show the same objects as two verified tens and four singles, explicitly replacing the arrangement. Check 24 both ways. This comparison revisits number structure; it does not claim completion of flexible partition or sharing outcomes.
Own choice · 6 minutes
Choose one route; the child selects/directs the mathematical action. A different route is available later.
Route A · Label rack
Child task: Repair a thirty-two-mark arrangement with one three-mark and one one-mark “pair”; count the repaired collection.
Teacher move: Ask which two boxes need membership checking; let the child choose the move.
Observe: Thirty-two retained, sixteen genuine pairs and cumulative 2…32.
Next move: If only the label changes, carry out the child’s proposed membership repair, then check a different defect.
Route B · Display plan
Child task: Show twenty-four as twelve pairs or two tens/four singles; compare totals.
Teacher move: Remove replaced groups from the old location; ask what each representation counts.
Observe: Same objects/twenty-four; no old/new duplicate total.
Next move: If the child adds both models, match one object set to both drawings and teach replacement on a fresh small set.
Route C · Count-list editor
Child task: For twenty paired marks, inspect 2,4,8,10,12,14,16,18,20. Find the first break and repair the account.
Teacher move: Ask which actual pair makes the third cumulative count.
Observe: Third count should 6; the account missed 6, rather than the objects becoming fewer.
Next move: If the error is guessed without quantity support, line up the first three pairs and reconnect 2,4,6.
Exit and same-day next teaching · 3 minutes
Four groups are labelled “pairs” but contain 2,3,1,2. Is counting 2,4,6,8 justified yet? Explain or repair.
Teaching reference: Total 8, but equal-pair grouping is not yet justified; move one from 3 to 1 for four true pairs. A correct total alone does not establish equal groups.
Choose next: Teach membership audit separately from the total. A child may know 8 while needing grouping support; retain both observations.
Retain the first response, actual range and support; a later corrected or adult-supplied model is a separate record.