# C15 · After-own staff

## Complete neutral brief

Need exactly 12 items for a fictional class activity. Pretend A packs 3 for $9; B packs 4 for $16. Whole packs and no extras. Compare full costs for the same quantity. Work out the whole-dollar cost of one item in each offer. Explain how those unit costs help you check the full-cost comparison.

## Specific criterion

Compare two whole-pack offers for the same required quantity and explain a whole-dollar unit cost.

## One staff worked possibility

A:4 packs/$36. B:3 packs/$48. Both supply 12 items; A costs $12 less. A costs $9 ÷ 3 = $3 per item; B costs $16 ÷ 4 = $4 per item. For 12 items, 12 × $3 = $36 and 12 × $4 = $48, matching the whole-pack totals.

## Neutral support limit

Ask one neutral 'What does that amount count?' question if necessary and record it. Teach afterwards rather than covertly supplying the model.

## Evidence scope

An individual response in a selected mode. Read/scribe if needed and record support; hide the teacher model first. Formative partial evidence, not an annual grade.