Can you open one ten without making more? Use the supplied ordinary amount, 38. Tell your helper how to exchange one full ten-strip for single marks.
- Begin with three checked full ten-strips and eight loose ones. Show the starting amount.
- Choose one strip. Replace its ten represented marks with ten singles. Remove that old strip from the active account.
- Check the remaining full strips and all the loose marks. Has each original mark been included once? What stayed the same?
Point, speak, sign, use AAC or tell a helper where to put the marks. A quiet private try or pause is fine. No photo, returned homework, purchase or independent drawing/moving is needed.
Grown-up help
**Prepare.** Make strips with ten separate cells, one mark per cell, and verify each before use. The original ordinary standard account is 30 + 8 = 38. Have space for replacement singles and an out-of-use place for the exchanged strip. The child directs; you may make/move the marks. Physical cutting, printing or handling is unnecessary. **Actual exchange and check.** After the child chooses the exchange, represent exactly the selected strip's ten marks as ten singles and remove its old strip. Keep the other two strips and original eight singles. The new account is 20 + 18 = 38; eighteen singles is a valid nonstandard account here. Audit the two ten-units and all eighteen singles, or track the same represented members before/after. Keeping the old strip as well would duplicate ten. A spoken proposed exchange remains a plan unless it is enacted; the child's mathematical explanation and adult operation are separately named. **Smaller or next.** Use one verified ten and a few manageable ones to rehearse the same replace-and-remove action, naming the actual smaller whole. Below-ten partition practice is useful but does not establish an exchange of a ten. Stop privately if wanted. If the amount changes, inspect one smaller exchange rather than demand another finished page. [Full plan](../teacher/day-45.md). Preserve first thinking and any hint; no home evidence count.Original SubjectNest teaching and drawings © NeuroForgeIO Pty Ltd 2026, CC BY 4.0. Credit SubjectNest by NeuroForgeIO Pty Ltd, version 0.1.0, source and licence; note changes. Curriculum and provider rights remain separate.