Tests of Dyslexia (TOD)

The Tests of Dyslexia (TOD) is the first comprehensive assessment of dyslexia, eliminating the need to use tests from different assessments. Linking dyslexia assessment to targeted interventions has never been more efficient and effective.

 

 

 

 

The Tests of Dyslexia (TOD) consists of three (3) sets of direct assessments: TOD-Screener (TOD-S), TOD-Early (TOD-E), and TOD-Comprehensive (TOD-C). The tests measure skills and abilities across three domains: reading and spelling; linguistic processing; and vocabulary and reasoning. TOD Parent/Caregiver, Teacher, and Self-Rating Scales gather data on indicators of dyslexia such as family history of reading problems, motivation, and early speech or language difficulties.

 

Together, the tests can help you create a profile of reading, spelling, and linguistic abilities to identify those who have characteristics consistent with a dyslexia diagnosis. The Dyslexia Interventions and Recommendations: A Companion Guide to the Tests of Dyslexia (TOD) links assessment data to evidence-based intervention recommendations so you can plan instruction based on individual strengths and needs.

 

Age-based and grade-based standard scores, percentile ranks, confidence intervals, and age- and grade-equivalent scores for each TOD test; Dyslexia Risk Index (TOD-S); Early Dyslexia Diagnostic Index (TOD-E); Dyslexia Diagnostic Index (TOD-C); composite scores in the domains of reading and spelling, linguistic processing, and vocabulary and reasoning; growth scores for monitoring progress. Co-normed TOD Rating Scales provide T-scores, percentile ranks, confidence intervals, and level of risk.

 

The TOD offers flexible testing configurations, standalone test options, as well as supplemental composites. The TOD-C generates 15 composite scores, and the TOD-E generates 4 composite scores, allowing practitioners to tailor each assessment to the needs of students.

 

Decades of reading research have identified the linguistic skills that underlie reading and spelling abilities, as well as those that are typically affected by dyslexia. In alignment with that research, the TOD measures:

 

This quick screener can be used with individuals or groups to provide a Dyslexia Risk Index (DRI) to show whether a more comprehensive assessment is needed.

 

TOD-S tests include:

 

The TOD-C provides a comprehensive dyslexia assessment which yields a Dyslexia Diagnostic Index (DDI) indicating the probability that an individual has dyslexia. The DDI is based on 2 tests from the TOD-S and 6 additional tests from the TOD-C. Another 14 tests provide a detailed look at skills and abilities related to dyslexia.

 

TOD-C tests include:

 

The TOD-E assesses each of the early abilities that most clearly indicate dyslexia in young children, yielding an Early Dyslexia Diagnostic Index (EDDI) score. Two TOD-S tests, along with the 6 TOD-E tests, indicate an individual’s risk of dyslexia.  

 

TOD-E tests include:

 

TOD-C and TOD-E Parent/Caregiver Rating Scales for grades K through 12 (available in English and Spanish) provide information about:

 

TOD-C and TOD-E Teacher Rating Scales provide information about:

 

TOD-C Self-Rating Scales for Grade 1 through adulthood provide information about:

 

This practical, evidence-based companion guide (referred to as the TOD Intervention Guidebook) helps practitioners link detailed interventions and recommendations to assessment data. Based on a structured literacy approach, the guide contains hundreds of strategies and activities grounded in the Science of Reading. It can be used by teachers, clinicians, and families to focus instruction and create a more supportive, effective learning environment.

 

The Individuals with Disabilities Education Act (IDEA) describes three methods for identifying dyslexia and other learning disabilities:   

 

Although a dyslexia diagnosis should not be based solely on the results of any single assessment, data from the TOD can be effectively used with any of the three IDEA models, subject to the requirements of individual states and school districts.

 

Comparing vocabulary and/or reasoning composites to reading and spelling composites can provide evidence of discrepancy. For example, when vocabulary and reasoning scores are higher than reading and spelling scores, the difficulties in reading and spelling can be viewed as “unexpected” given verbal comprehension and reasoning abilities.

 

TOD composites may also indicate a pattern of strengths and weaknesses that is common in individuals with dyslexia: difficulties in reading and spelling, paired with one or more significant linguistic weaknesses, and strong verbal comprehension and/or reasoning ability. TOD composites can be used to confirm such a pattern normatively or intra-individually.

 

In school districts where students have received evidence-based instruction in a tiered setting, TOD-C standard scores based on national norms can confirm whether a student’s performance and progress are acceptable, or whether a diagnosis of SLD or another condition may be appropriate.

 

The TOD Manual provides detailed guidance on identifying dyslexia probability using each of these models.

 

TOD standard scores and growth scores can be used to monitor progress over time. Standard scores are norm-referenced based on age or grade; therefore, achieving the same standard score after a year indicates that a student’s reading scores have increased at the same rate as those of other same-age or same-grade students. Growth scores show an individual’s progress compared to their own previous performance. Growth scores are sensitive to smaller changes, so an improvement of ten points or more indicates meaningful growth in a skill or ability. Used together, standard and growth scores can provide a clear picture of change.

 

 

How schools can use the TOD to transform education for students with dyslexia: