Intelligence test scores are most likely to be stable over a one-year period for an eleventh-grade student.
Research has shown that intelligence test scores tend to become more stable as individuals get older. This stability increases throughout childhood and adolescence, with scores becoming more consistent by the time students reach high school. Therefore, eleventh-grade students are likely to have relatively stable intelligence test scores over a one-year period compared to preschool, fifth-grade, or third-grade students.