TerraNova is a standardized achievement test for students in grades k-12. The OPI, or "Objective Performance Index," is a score that shows the student's performance on the test.
TerraNova and OPI are standardized state tests. OPI tests listening comprehension and speaking ability. The TerraNova tests achievement in reading, language arts, math, science, social studies, vocabulary, and spelling.
Terra Nova standardized testing that is used in grades K-12 in the U. S. OPI measures an individual's grasp of the English language in terms of speaking, expression and comprehension. When you meet with your son's teacher, make sure to ask her to explain things you do not understand.
These are testing criteria based on standard tests. I feel it is inappropriate to worry about this at 1st grade level, where a child should be learning basic skills and love of learning. I would be questioning a school system that is concerned with standardized testing at such a young level. They should be considering your child, not a "grid".