What do the numbers mean? What is ability and acheivement? I'm drowing in numbers.. HELP!

Making sense of all the numerical and statistical data when a child is being tested for a learning disability seems as if it needs its own advanced degree just to navigate!

The first thing that should happen on the road to diagnosing a learning disability is for the school to request your permission to test your child. Generally there will be two different tests given, each measuring a specific thing.

The first test will be an ability test, a cognitive assessment of what your child should be able to do. Alfred Binet created the first test that he believed would reliably assess the intelligence of a person back in 1904.  Over 100 years later, the tests have gone through numerous updates, and the tests go through tests themselves to ensure they measure what they are intended to measure. There are several out there, but the most common seems to be the WISC, the Stanford-Binet (still being used today!!!) and the DAS, or Differential Ability Scale.  Most of these tests are verbal tests, meaning the student needs to be able to understand language and directions.  For children for whom this is not possible (think ELL students or students so young as to not have the adaptive language for such tasks) there are also tests which are non-verbal in nature but that accurately measure the same things as, say, the WISC.

So, what are they measuring?  Generally tests break up tasks into two areas: verbal and performance.  Students are asked questions like "why would a firefighter wear a uniform" or asked to complete a maze or replicate a design with blocks. Processing speed and memory are also measured.  From these tests, a Full Scale Performance IQ is determined.  It is rare to see this number change much over the years, although a variation a few points is to be expected when the tests are given 3 years apart.

So, what numbers do we want to see, and what REALLY are we measuring?  Well, if you are so inclined to think of it this way, the IQ is your God-given ability - it is what you were born with. It is not the result of schooling (think Einstein and Edison) but rather your innate talents and gifts.  The scale ranges from 10 to 250+, but generally you see 100 as an average, and that is the number used by educators as we look to the MEAN of the scale. We consider the "average range" to be from 85 - 115, or 1 standard deviation away from the norm, with a standard deviation being equal to 15 points on the scale.  From here, we know what we should be able to expect from your child in school.  Ideally, a child with 100 as an IQ would also ACHIEVE around a 100.

The achievement tests measure what the child has absorbed, retained and garnered from his school life.  Specific academic skills are measures such as spelling, writing, math reasoning (where you have to manipulate numbers in your head.. word problems), math calculations, reading decoding, reading comprehension and listening/speaking skills.  These tests work off the same 100-being-the-mean score, so the numbers do match apples for apples.

When the scores from achievement are significantly lower than the scores for ability, we presume that is due to a learning disability.  Other causes are possible such as academic deprivation which is generally not as abusive as it sounds - a child who was ill, for example, and missed 10 weeks of school would be considered to have lower achievement scores simply because she was not in school for all those days. 

Depending on the areas, a diagnosis of SLD would be given wherever there is a score greater than a standard deviation below the IQ, although it becomes more of a sliding scale depending on the IQ.. the higher the IQ, the greater the discrepancy needs to be and conversely, the lower the IQ, the smaller the discrepancy needs to be. 

It is common to see a child with scores that are close to their IQ in all areas but one, and it is just as common to see a disability in many, or all, areas.  These are highly unique, and there is no one-size-fits-all explanation.  If you have a question about your child's test scores, call his special education teacher or request a sit down or phone conference with the school psychologist or other professional who can interpret those results for you.  You have the right to have all of your questions answered, and I hope I have clarified some things here today.

Educationally yours,

The SpEd Guru