Home 37 · Unknown stays unknown
Try one little turn.
Prepare: Describe four known card labels sun,moon,sun,star plus one unavailable.
Invitation: Invite a table and a statement about what is still unknown. Do not reveal the missing record as a trick.
Adult model/check: MODEL: sun 2,moon 1,star 1,total 4 known; unavailable 1,total 5 records. A listed planet 0 is 0 among known only, not proof the unknown is not planet.
Observe and respond: Ask for one useful reason; keep the child's response as actually made. If unknown is counted aszero, contrast a genuinely empty known category with an unseen record in a new example.
Usual communication, wanted exact scribing, private/untimed work, rest and stopping are welcome. No purchase, photo or upload. A model is not an observation of your home; actual child mathematical choice, helper physical action and any real willing-reader trial are separately named.