Codes: AC9M3N03, AC9M3A02. Target: add 268 + 157 by place-value regrouping, no calculator. Set out: hundreds/tens/ones cards, paper exchange tokens.
- Frame · 2 min. Ask: “About how much is 268 + 157?” Accept
about 270 + 160 = 430as a benchmark, not an exact answer. - Model · 5 min. Build 268 and 157. Combine ones: 8 + 7 = 15, exchange 10 ones for 1 ten. Combine tens: 6 + 5 + 1 = 12 tens, exchange 10 tens for 1 hundred. Combine hundreds: 2 + 1 + 1 = 4. Say: “The total is 425. It is close to our estimate.”
- Guided example · 6 min. Solve 146 + 185 together. Learners direct exchanges: 6 + 5 = 11 ones; 4 + 8 + 1 = 13 tens; 1 + 1 + 1 = 3 hundreds, 3 tens, 1 one → 331. Check by subtracting 185 if ready.
- Partner practice · 7 min. Offer 237 + 148 and 356 + 129; both equal 385 and 485 respectively. One partner explains the exchange, the other checks with a different decomposition. Use a two-digit example if needed while preserving exchange logic.
- Talk about errors · 3 min. Show
268 + 157 = 315and ask what happened to an exchanged hundred. Return to the models; do not simply say “carry the one.” - Brief check · 2 min. Everyone works 184 + 137 = 321 and points to the ten made from 4 + 7 ones. Focus learners explain an exchange or an alternative valid strategy.
Access: enlarged cards, tactile bundles, partner handling under learner direction, speech/AAC/drawing. Value reasoning matters more than neat columns.