Target/codes: transfer OPENING · DIFFERENT · RETURN from pitch L/H to a familiar A/B electronic source key, preserving the section rule; AC9AMUFD01. Prepare: F source-key transfer, Practice F, broad circle/striped-square source cards.
- Welcome · 3 min. Section names are not A/B; A and B here label invented electronic tone recipes only.
- Model · 4 min. Lay source opening
B A, middleB B, finalB A. Show that the two-event opening returns exactly even when the key is source, not pitch. - Try together · 5 min. Child checks final against opening first-to-first/second-to-second and marks where middle differs.
- Child choice · 7 min. Child chooses A/B cards for a fictional paper map visitor pause or a plain score, then says which pair returned. No real route or community instrument is implied.
- Notice · 4 min. Save six source labels and the child's reason. Actual timbre hearing is a separate event, not assumed from symbols.
- Close · 2 min. Tomorrow the child may choose the key and author all three sections.