A nine‐point scale was devised for scoring drawings of a cube. Clear and detailed criteria and examples of each category are provided. A total of 489 children between the ages of 5;2 and 13;7 in primary and secondary schools observed and drew a cube. The inter‐rater reliability of the nine‐point scale is high and the scores show a linear trend through the age‐range. The scale is suitable for use by teachers as a diagnostic or assessment task for children's observational drawing or by researchers in their studies of children's representational drawings of solid objects.