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This article describes a comprehensive and novel approach to assessment in early numeracy. Topics include the significance of early numeracy, developing a nomenclature for early numeracy, and describing the context for the development of this approach to assessment. The largely unrealised importance of numerals and numeral sequences in early numeracy, the significance of counting and its distinction from saying a number word sequence, the important topics of structuring numbers in the range 1 to 20 and conceptual place value, the Learning Framework in Number and its use in profiling children’s early numeracy knowledge, and important assessment tasks are explored.

Dimeric arylgallium/indium chalcogenides 7−10of formula [Ar′ME]2(Ar′ = C6H3-2,6-(C6H3-2,6-Pri2)2; M = Ga or In, E = O or S) were synthesized by the treatment of Ar′MMAr′ with N2O or elemental sulfur and characterized by NMR spectroscopy and X-ray crystallography. Their structures feature three-coordinate, +3 oxidation state metal centers with planar M2E2cores. The cores were almost perfectly square for E = O, but for E = S, they were distorted parallelograms in 7−10. The M–E bond lengths were shorter than those in the higher aggregated species [RME]n(n≥ 4) but comparable to those in M3+aryloxides or thiolates featuring three-coordinate metals. Short M···M separations [2.553(1) Å in 7, 2.8882(4) Å in 8, 2.8276 Å (avg.) in 9, and 3.1577(8) Å in 10] are observed. Low oxidation heavier group 13/group 16 chalcogenolate isomers 16−19of formula [Ar′EM]2(M = In or Tl, E = O or S) were also synthesized and characterized. In the +1 compounds [Ar′EIn]2(O, 16; S, 19) together, with the In +3 species [Ar′InE]2(O, 8; S, 10), represent the first structurally characterized isomeric pairs of organo group 13 metal/chalcogen derivatives. The E−M bonds in 16−19were 2.3329 (avg.), 2.560 (avg.), 2.8189 (avg.), and 2.897 Å (avg.), respectively, which are 0.3−0.4 Å longer than the corresponding In−chalcogen distances in 8and 10as a result of the lower oxidation state, the large In+ionic size, and the reduced ionic contribution to the bond strength in 16and 19. The compounds 16−19also displayed M−arene interactions to the flanking aryl rings of the Ar′ ligands. The Tl−arene contacts in the crystal structure of 17are preserved in solution, as evidenced by 13C−Tl coupling. Attempts to thermally interconvert the isomeric pairs 8, 10and 16, 18led to decomposition of the complexes. [ABSTRACT FROM AUTHOR]