Gather by the hollow log. "When two piles come together, we add," says Biscuit. Model adding the big bundles first. Work 2 350 + 1 425 aloud:
Then model a sum that needs carrying — 1 675 + 1 248 — showing that when a column makes more than 9, the extra bundle trades up to the next column, just like trading ten tens for a hundred.
Together 1. 1 200 + 650 by adding the parts.
Together 2. 3 060 + 2 970 — watch the carry from the tens.
Together 3. On Harvest Day the friends gathered 1 850 gumnuts in the morning and 2 340 in the afternoon. What was the day's total?
Students complete "Combining the Gumnut Piles: Addition". The support version stays with two-digit splits; the extension version adds larger sums and addition puzzles. Circulate and prompt students to estimate first ("about 4 000?") so they can check their answer is reasonable.