My younget took it at 6 as part of the screening for the gifted program. They adminster both the K-Bit and the TOMAGS and based on those results will determine if they do a full scale WISC. He is a very math-y kid, and very literal. (Frustratingly literal.) He would not have scored high enough to warrant further testing if they looked at just the K-Bit (his score was in 92%), but the 99.9% on the TOMAGS warranted the WISC, on which he scored 145. So for us, the k-bit was not at a good test for him, but I think it's more about the type of learner/person he is rather than his age.