# Day 65 — Empty, equal and twenty

**25 minutes · AC9MFN01 review; AC9MFN03 · educator review pending**

**Success:** Child represents zero with an empty bounded set, compares it with a nonempty set, and checks a near-twenty comparison or equality using counted objects. Saying `0` alone without an empty set is not enough evidence.

**Prepare:** [C06](print-aids.md) (A0/B8), [C05](print-aids.md) (A19/B20), and [C10](print-aids.md) (17/17) as an alternative; trays, counters, numeral cards 0, 8, 17, 19, 20. Check set A=0/B=6, then A=20/B=15 if ready.

1. **Retrieve, 3 min.** Point to an empty A tray and ask, “How many counters are inside this boundary?” Accept zero and link it to `0`.
2. **Model, 5 min.** Read C06. Pairing gives no pairs and eight B counters unmatched. Say, “A has zero; B has eight, so B has more.” Count B carefully; never call the empty tray “missing data.”
3. **Partner stations, 10 min.** Pairs try C06 then C05, counting A19 and B20 and pairing to find one unmatched B. If needed, swap C05 for C10 equality and return to nineteen/twenty in a later small group. Teacher observes three learners' count across the teen sequence and use of `0`.
4. **Fresh check, 4 min.** Start A empty and B six: child identifies 0/6 and relation. For learners ready for the stated scope, follow with a new A20/B15 layout and ask for a count and comparison; record each separately.
5. **Close, 3 min.** Ask how “zero” differs from “not checked yet.” **Key:** C06 0/8 B more; C05 19/20 B more by one; C10 17/17 equal; fresh 0/6 B more, extension 20/15 A more by five.

**If a child counts an empty tray as one:** Keep the boundary visible and ask what object the word “one” would name; do not put an object in simply to cue the answer. **Access and record:** An empty tactile tray and numeral card can be explored by touch; child may use AAC or spoken response. Record which near-twenty set was actually checked, since zero work alone does not establish comparison to 20.