At age 5, you would need an individually administered achievement test: he is too young for any of the talent search/college placement test (even EXPLORE only goes down to 3rd grade). The options are KTEA-II, WIAT-II, WIAT-III, or WJ-III. Any of these would need to be administered by a qualified psychologist. You might be able to get the school to administer it if there is an educational reason, but I wouldn't count on it. You can get this kind of testing for a few hundred dollars around here - call around local psychologists and see what they say.