Influence of age, ability, and angle on pupils' judgments of size of angles

80 subjects of 11 to 14 years were tested with 8 cards on which were printed angles between 0 degrees and 180 degrees, and on the Raven's Progressive Matrices Test and the Schonell R4 Reading Test. Significant differences on performance were found in relation to age and ability variables and as between angle sizes 0 degrees--90 degrees and 90 degrees--180 degrees.