The one prekindergarten skill that matters above all others, because it is the prime predictor of school success or failure, is the child’s vocabulary upon entering school. Yes, the child goes to school to learn new words, but the words he already knows determine how much of what the teacher says will be understood. And since most instruction for the first four years of school is oral, the child who has the largest vocabulary will understand the most, while the child with the smallest vocabulary will grasp the least.
