Just found this link:

http://learningandlifeskills.typepa...-lennon-school-abilities-test-olsat.html

"Notice how the skillsets being assessed change once a child reaches 3rd grade - moving from a heavy dependence on figure-based reasoning to more verbal-based reasoning tasks. Notice also that students are not assessed for quantitative reasoning until 3rd grade, as well."

Perhaps this is the reason for the "lower" score.