Goal: keep the total when 10 loose ones exchange for another ten. Prepare: five verified strips, ten ones, sixth strip, Day 12 cards.
- Notice, 3: Build 58 as five tens and eight ones. Add one; ask what numeral comes next. Key: 59.
- Model, 5: Add a tenth loose one to 59, touch-count the ten loose objects, then replace them with one full ten-strip without changing the total. Show 5 tens + 10 ones = 6 tens + 0 ones = 60. Do not call the zero “no quantity”; it means no loose ones.
- Guided, 8: Learners use A (sports club: five drawn strips of ten tickets and eight loose) and B (maker bench: five racks of ten bolt symbols and nine loose). Move one from A to B's quantity, then one more to 60. Verify 58 < 59 < 60 with quantities and chart order.
- Independent, 6: Use C (music editor: six bars of ten beat marks). Learner shows 60 in two equivalent forms, such as six strips or five strips plus ten loose. Ask what immediately precedes 60.
- Exit, 3: Show five tens and ten ones. Ask for a single numeral and an equivalent exchanged model. Key: 60 and six tens/zero ones. If “510” appears, physically audit and trade the ten ones; recheck with 29 + 1 before moving ahead.