25 minutes · AC9MFN04 (partition/combine up to ten); AC9MFN01 and AC9MFN03 (0–20 retrieval); partial practice · educator review pending
Success: The child independently builds a whole up to ten, shows two valid splits, reunites each and explains or demonstrates that the whole stayed the same.
Prepare per pair: ten counters, part-whole mat, whole cards 5/7/8/10, two comparison mats and scene cards. Keep the assessment for short individual evidence over the day, not a full-class speed test.
- Retrieve, 3 min. Show 19 and 20 on the number path. Ask which has more. Briefly show a familiar four-dot grouping and ask what the child saw; record the visual/tactile route separately.
- Model, 5 min. Choose a pretend workshop order of eight tool cards. Split as five and three, combine all eight, then move one object to show four and four. Say, “The parts changed. The whole did not, because no object left or joined.”
- Guided game, 10 min. Partners choose a whole 5, 7 or 10 and a scene: parcel shelves, space equipment bins, construction containers or a setting they invent. They build the whole, make two splits with different part sizes and reunite after each. Swapping the left and right parts alone does not count as a new combination. One checks that every object was used once, then swap. A solo route uses the same steps.
- Fresh try, 4 min. Give eight objects and a blank mat. “Show the whole eight. Make one split and then a split with different part sizes. Show the whole is still eight.” Do not propose the pairs before the child tries. A smaller route uses five and is recorded as such.
- Check, 3 min. “If I have four and four, what is the whole? If I move one from one part to the other, what are the parts now?” Key: 4 and 4 make 8; moving one from the first part to the second gives 3 and 5, still 8. In the retrieve, 20 > 19 by one; four dots total four.
If a split seems correct only after the partner tells it: Give a new private whole and watch the child's own placement. If the child says a new total after merely moving an object between parts, recombine the same objects and count. Use assessment.md to choose the next lesson, not to attach a fixed label.
Access and record: Raised mat, grippable counters, large numerals, spoken/tactile layout, sign, AAC, gaze and directed partner movement are all valid routes. Record each actual split, the recombined whole, independent versus cued response and the next specific teaching move.