Number Bonds within 20

Students build number bonds within 20 on two tens frames — one full frame of ten plus the second frame part-filled (9 + 7 = 16) — and find the pairs that make 20 (12 + 8). Each bond is written as a family (9 + 7 = 16; 7 + 9 = 16; 16 − 7 = 9; 16 − 9 = 7) and in the = first forms the NC names (16 = 9 + 7; 7 = 16 − 9), so the statutory missing-number sentence 7 = ? − 9 (answer 16) is met here, supported by the bond. Extends 1NF–1 beyond 10 and is the base for Y2's across-10 work (2AS–1); the formal make-ten strategy itself remains Y2.