Useful outcome: Recognise, continue and create a sequence whose quantities grow by two.
Prepare: Separate stages with 2,4,6,8 square marks; blank stage spaces; number cards 12–22 as needed. No colour discrimination, cutting or handwriting is required.
Notice · 3 minutes
Show stages 2,4,6. Ask what changes from one stage to the next. If the child notices colour/shape, accept the observation then ask about how many marks. These are increasing quantities, not an ABAB repeating unit.
Model · 5 minutes
Make 2,4,6,8-square stages by keeping the earlier marks and adding a pair. Next is 10. Label the total at each stage or direct an adult to label it. Show that the label 10 alone does not prove there are ten actual marks.
Guided attempt · 8 minutes
Begin with twelve marks, then add one pair for 14, another for 16, then 18 and 20. The given start stays included. Ask the child to identify the two new marks in one transition. Permit an object row, chosen shape marks or symbols whose unit meaning is agreed.
Own choice · 6 minutes
Choose one route; the child selects/directs the mathematical action. A different route is available later.
Route A · Picture trail
Child task: Choose an own mark/symbol and make four stages that grow by two; show a next stage.
Teacher move: Ask what was added at each transition; do not select the child’s mark or draw the mathematical increase for them.
Observe: Own stage quantities follow one two-object change; representation and labels agree.
Next move: If it is a repeating decoration only, contrast 2/4/6 growing quantities and ask for a new three-stage creation.
Route B · Numbered path
Child task: Start at 12; continue 14,16,18,20 and choose the next label with an object explanation.
Teacher move: Retain the twelve base and invite one new pair at a time.
Observe: The start is included; the next value is 22, with a two-object change.
Next move: If the child restarts at 2, physically retain the base then add one pair and recheck from a different start.
Route C · Same rule, new form
Child task: Create a twos sequence in one form and direct another form for the same stages.
Teacher move: Ask which quantity in one version corresponds to which quantity in the other.
Observe: Equivalent stages; the child, not the adult, chooses the rule and totals.
Next move: If labels and objects conflict, check one transition and ask for a fresh own third stage.
Exit and same-day next teaching · 3 minutes
Show 4,6,8 and state that each next stage adds two marks. Ask for the next quantity and an own way to show it.
Teaching reference: 10 with a supported two-object addition. Other starting points are valid in a separate own sequence, but the stated rule governs this item.
Choose next: Separate recognising a provided rule, continuing it and creating an own example. Plan another creation if only copying was observed.
Retain the first response, actual range and support; a later corrected or adult-supplied model is a separate record.