The study took place at the Experimental Education Unit of the University of Washington’s Child Development and Mental Retardation Center. Preschool classes were two
hours a day, five days a week for 180 days, and kindergarten classes were five and a half hours a day, five days a week for 180 days.
This study included 164 preschool and kindergarten children from a larger study. They had no previous preschool experience. Eighty-one children were in the intervention
group and 83 children were in the comparison group. Individual children were first randomly assigned to a Direct Instruction intervention group or a Mediated Learning comparison
group; then children in each condition were randomly assigned to classrooms (six preschool classes and two kindergarten classes). All the children had disabilities,
including language delay (80%), cognitive delay (50%), fine motor delay (60%), gross motor delay (60%), and socio-emotional delay (60%). The mean age of the children in
the sample was 4.75 years, their mean IQ was 76.03, and 32% were female. Sixty-two percent of the children were European-American, 29% were African-American, and
10% were Hispanic, Pacific Islander, Asian, Native American, or another race/ethnicity.
The WWC designated the Direct Instruction condition as the intervention for this review. The intervention condition included the Direct Instruction programs DISTAR Arithmetic,
DISTAR Reading, and DISTAR Language, which are academically-oriented programs characterized by instruction that is fast-paced, teacher-directed, prescribed, and explicit,
with all children receiving instruction on a pre-specified sequence of activities at the same time. Although there is information on the length of each school program, there is
no information about the duration or frequency of Direct Instruction.
The WWC designated the Mediated Learning condition as the comparison condition for this review. The Mediated Learning curriculum included units that were two to three
weeks long and focused on topics such as identifying patterns, making comparisons, identifying feelings, and planning ahead. Mediated Learning is a cognitively-oriented,
non-academic program that emphasizes processes related to input, elaboration, and output. As opposed to the direct approach used by teachers of Direct Instruction, teachers
using Mediated Learning scaffold children’s learning around cognitive processes such as classification and sequencing. Although there is information on the length of each
school program, there is no information about the duration or frequency of Mediated Learning.
The primary outcome domains assessed were children’s oral language, print knowledge, cognition, and math. Oral language was assessed with five standardized measures and one non-standardized measure. The standardized measures include: the McCarthy Scales of Children’s Abilities (MSCA) Verbal Scale; the Peabody Picture Vocabulary Test-Revised (PPVT-R); the Test of Early Language Development (TELD); the Preschool Language Assessment Inventory (PLAI); and the Basic Language Concepts Test-Errors (BLCT; criterion referenced measure). The non-standardized measure is the Mean Length of Utterance (MLU) derived from language samples. Print knowledge was assessed with one standardized measure, the Test of Early Reading Ability (TERA). Cognition was assessed with three standardized measures, the MSCA Composite Scale (General Cognitive Index), the MSCA Perceptual Scale, and the MSCA Memory Scale. Math was assessed with one standardized measure, the MSCA Quantitative Scale (see Appendices A2.1–2.4 for detailed descriptions of outcome measures). Data analyses were based on the children’s scores after the first year of participation in the four-year study period.
Support for implementation
Each class was staffed by a head teacher and an assistant teacher. Other staff included related services personnel and practicum students. All head teachers had Master’s degrees in special education. Of the eight Direct Instruction head teachers, three received their degrees from a University of Oregon program that emphasized Direct Instruction, four received in-service training from that program, and one was trained on-site. Two of the Mediated Learning teachers were trained in Mediated Learning at Vanderbilt University and two additional teachers received training from Dr. Feuerstein (an Israeli psychologist whose work is the basis for Mediated Learning) and consultation on curriculum and procedures. The five additional teachers in the Mediated Learning program received ongoing professional development from the teachers who were trained at Vanderbilt.