McCoach describes three types of gifted/learning disabled students. The first student does well in elementary school when the learning disabilities are less distinct and they still participate in gifted programs. As the work progresses within that student's disability, he/she may begin to experience learning difficulties which leads to underachievement. These students are not normally identified as learning disabled due to the high achievement in elementary school. The second type is described as learning disabled but also gifted. Since such students have severe learning disabilities, they are seldom identified as gifted. The third type is the student that is not identified as either gifted or disabled. This student's disabilities hide their gifts and the gifts conceal their disability, creating a smokescreen which is referred to as "masking" within the definition of gifted/learning disabled students. "Masking refers to the principle that many gifted students with learning disabilities have patterns of strengths and weaknesses that make them appear to have average abilities and achievement". So therefore, these students do not get identified as gifted or learning disabled. Some advocates believe that intelligence scores will be lower for these students, "thereby hindering their identification as either gifted or learning disabled" . " the primary problem with the use of intelligence test to identify gifted students with LD is that the disability may lower their IQ score so dramatically that the students do not qualify for inclusion in the school district's criteria for gifted, even though they demonstrate strong abilities in some areas.