Table 1.

Means, range standard deviations (SD) and scores corresponding to the proband cut-offs for the three mathematics measures

Measure	Total number of items in category	Cut-off (%)	Range of items (min–max) for probands	Mean (SD) for probands	Link to the National Curriculum level and standardization informationa
Understanding number	27	85	25–27	26.18 (.62)	All children perform above their grade-level difficulty, solving items as high as level 5, recommended for children in the following year of education
Non-numerical processes	19	85	16–19	17.49 (.71)	Most children perform above their grade-level difficulty, solving items as high as levels 5 and 6, recommended for children in the following year of education
Computation and knowledge	31	85	30–31	30.66 (.46)	The top items are as difficult as level 5, recommended for children in the following year of education

^aNational Curriculum uses seven levels (level 8 = exceptional performance). Children at Key Stage 2 (7–11 year-olds) are expected to work with levels 2–5, and most children are expected to attain level 4 by the end of the year during which we tested our sample