The discrepancy model: What you need to know

At a glance

  • The discrepancy model is what some schools use to determine whether kids are eligible for special education services.

  • The term “discrepancy” refers to a mismatch between a child’s intellectual ability and their progress in school.

  • Some states now use other methods to determine who is eligible for services.

Is your child being evaluated for special education? If so, you may read or hear about something called “the discrepancy model.”

Historically, schools used this model to determine if a child had a learning difference that qualified them for services. But there are differences of opinion among professionals about the benefits and drawbacks of this approach.

Many schools still use the discrepancy model. But many others are now using different models. Here’s what you need to know.

What is the discrepancy model?

The discrepancy model is a way to capture and compare a student’s scores on different types of tests. It compares assessments of a child’s intellectual ability () with how much progress they’re making in school (academic achievement).

In some cases, there may be a large “discrepancy” (difference) between various sets of scores. The idea is that when there’s a difference like this, it’s evidence that an underlying condition is making it unusually hard for a child to learn.

For example, say your fifth grader’s IQ falls in the average range. The expectation would be for them to be reading at a typical fifth-grade level. But say your child’s scores show that they’re actually reading at a second-grade level. In that case, there’s a discrepancy between what the IQ test said your child is capable of (ability) and their actual reading level (achievement).

How the discrepancy model is used

The discrepancy model was part of the Individuals with Disabilities Education Act (IDEA) when it became law in 1975. It was created so that schools would have a way to figure out which students were eligible for special education.

For decades, schools were required to use the discrepancy model. But in 2004, when IDEA was reauthorized, that changed. The law now says that states can use the discrepancy model if they choose. However, it allows them to use other models instead of or along with the discrepancy model.

Thirty-nine states still allow their school districts to use the discrepancy model. Eleven states forbid its use.

Benefits and drawbacks of the discrepancy model

Professionals and schools say that some benefits of the discrepancy model are:

  • It’s already an established practice. Schools have been using it for many years.

  • It demands little or no time from classroom teachers. Testing is done by a separate team of professionals.

  • It requires getting subtest scores on different measures of cognitive processing. These scores could provide helpful information about underlying issues that might contribute to a child’s struggle. This is especially true for kids who have above-average intellectual ability but whose school performance doesn’t reflect their potential.

Professionals and schools say some drawbacks of the discrepancy model are:

  • The discrepancy model is still often the default. But when it’s used, it should always be considered along with other data to give a comprehensive assessment of the child. When the discrepancy model is used alone, just a point or two on a score can mean the difference between a child’s being eligible for special education services or not.

  • There are different standards about how big a discrepancy is considered significant. When they use the discrepancy model, each state or school district is allowed to decide how big the discrepancy between a child’s IQ and their achievement level must be in order for that child to be eligible for special education. So a child who is eligible in one state may not be eligible in another.

  • It can identify kids too late. Students with learning differences often struggle in the early grades. But they rarely show a large enough discrepancy on test scores to be “officially” identified with a learning difference. It’s generally not until third or fourth grade that the work gets hard enough for the discrepancy to become large enough. This can lead to a “wait to fail” situation: Kids don’t receive help until they’re doing poorly in school.

  • It doesn’t suggest what kind of help students need. Test results may show there’s a problem. But the scores alone don’t provide detailed information about performance and what specific kinds of instruction and support kids need.

  • It may not provide a “level playing field” for all students. Kids with cultural and language differences might not score as well as their peers on tests that don’t reflect those differences. That’s true even when they’re just as capable as their peers.

Other approaches used today

When IDEA was reissued in 2004, the law permitted alternatives to the discrepancy model. This change was intended to help schools identify children with learning differences earlier and get them the specific kinds of help they need.

One approach mentioned in the law was response to intervention (RTI). RTI looks at all students’ reading, writing, and math skills early in the school year. Then it provides targeted support to those who are struggling.

Children who don’t respond to increasing support may then be considered for special education. The benefits of RTI: Students get help early. And they don’t have to wait to prove eligibility in order to get support. Keep in mind that even if your child is receiving RTI, you still have the right to request an evaluation for special education services.

Another approach being used in some schools is called the “processing deficit approach.” This includes testing that helps teachers understand kids’ patterns of strengths and weaknesses. That allows them to modify how they teach to meet the kids’ needs.

For example, say a child has trouble processing information they hear. In this case, instruction might include written materials and/or other . The child’s teacher might give out notes before the instruction. The child might also get follow-up notes to reinforce their classroom learning.

Test scores and testing are still supposed to play a major role in identifying kids who need help. But in more and more cases, they’re not the only deciding factor. Educators now use data from RTI and MTSS (multi-tiered system of supports) activities and individualized assessments. This information helps them identify which kids need extra help and decide on teaching strategies.

What you can do

It’s up to your child’s school (and the state you live in) to decide how it will identify students who need special education services. But no matter the method, you have rights in the process.

Read more about your rights during the evaluation process. And get information on steps you can take if your child is denied services.

Key takeaways

  • When IDEA was reissued in 2004, it didn’t require schools to use the discrepancy model any longer.

  • The discrepancy model doesn’t take into account all the factors that may affect a child’s academic achievement.

  • Response to intervention and the processing deficit approach are two alternatives to the discrepancy model.


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