# Day 18 — Two full tens make twenty

**25 minutes · AC9MFN01 (20 representation and 18–20 order), AC9MFN03 (count and compare 19/20); partial practice · educator review pending**

**Success today:** The child builds 20 as two complete ten-frames, counts to verify, matches `20`, and demonstrates that 20 follows 19 by one.

**Prepare per pair:** two ten-frames, 20 counters, cards 18–20 and 0–20 path; see [print-aids.md](print-aids.md). If using a school-approved virtual counter tool as an optional transfer, check its accessibility and privacy settings first; physical objects remain available.

1. **Reconnect, 3 min.** Show 19 with one empty space in the second ten-frame. Ask what one more will do. Let a child fill the last space.
2. **Model, 6 min.** Say, “Both frames are full. One has ten and the other has ten. I will count the whole collection to check: twenty.” Place card `20` beside it. Remove one object to show 19, replace it to show 20. Put `18, 19, 20` on the path; each step adds one object.
3. **Play: playground plan, 9 min.** Partners make 19 chalk-spot markers for a pretend plan and add one to make 20; swap. Variants: 20 star cards for an observatory display or 20 container cards for a recycling centre. Children can choose paper marks or objects, but must check the total. A virtual counter version can repeat the same task after the physical model where available.
4. **Independent try, 4 min.** Show `18, 19, 20` mixed and give 20 uncounted objects. “Show twenty and place its card after nineteen. Take one away: what number now?” Observe the child's count and reasoning.
5. **Check and close, 3 min.** Show a full first frame and a second with nine filled. “Is this nineteen or twenty? What would make twenty?” **Key:** 19; one more makes 20; `18, 19, 20` is the order.

**If the child says 20 is two because it has two digits or frames:** Count the objects in each frame, then all twenty. If a child counts `...18, 19, 30`, practise the spoken 18–20 sequence with objects and path; score the object total separately from English naming when the numeral/quantity relation is shown by another response route.

**Access and record:** Offer a raised double frame, large/tactile whole-numeral cards, clear speech or home-language naming with the exact numeral, AAC choices and directed partner placement. Record 20-object build, card link, 19/20 one-object comparison, order and any virtual transfer separately.