# Day 31 — Two groups join

**25 minutes · AC9MFN05 (practical addition and quantification with objects); partial practice · educator review pending**

**Success:** The child represents two small groups joining and counts or recognises the new whole. The action, starting groups and result are visible.

**Prepare per pair:** ten large counters, two small mats, one whole mat and the [start/change/now page](print-aids.md). Use no edible counters.

1. **Retrieve, 3 min.** Show a whole of five split into two and three. Ask for each part and the whole; bring them together to verify five.
2. **Model, 6 min.** Put three paper “library books” on one mat and two on another. Say, “Three are here. Two more join them on the trolley. I move the two beside the three. Now I count the trolley: one to five. Five books are on it now.” Show `3 and 2 make 5` only after the objects.
3. **Guided game, 9 min.** Partners choose a pretend library trolley (3 join 2), an art tray (2 shapes join 4) or an animal shelter supply mat (4 bowl cards join 3). One acts out the joining; the other counts the new whole, then they swap. Ask which objects were present before and which joined.
4. **Fresh try, 4 min.** Place four objects on a mat and hand the child three more. “Add these to the mat. How many now? Show how you know.” Give no answer cue first.
5. **Check, 3 min.** Show two and three separated, then together. “Did joining change the number of objects across both mats, or only where they are?” **Key:** 2 and 3 make 5; independent 4 + 3 = 7; the five objects still total five when moved together.

**If the child counts only the newly joined group:** Sweep around the entire final set and count it. If they say “three plus two is six” while counting one object twice, move each counted object to a receiving mat exactly once.

**Access and record:** Offer tactile mat edges, grippable objects, large numeral choices and child-directed partner placement. Accept speech, sign, AAC, pointing or moving objects. Record both groups, the final total, whether counting all or small-group recognition was used, and prompts.