The study was conducted with children from 20 full-day preschools (54 classrooms: 27 Doors to Discovery™ and 27 comparison) selected from Head Start and public preschool programs in the greater Houston, Texas area.
This randomized controlled study, conducted during the 2003–04 school year, included three groups: Doors to Discovery™, Let’s Begin with the Letter People®, and a comparison group. Study authors recruited 32 Title I and non-Title I (universal) preschools and Head Start centers that included a total of 79 classrooms. Within each of the three school types (Title I, non-Title I, and Head Start), schools were randomly assigned to either the Doors to Discovery™ intervention group, the Let’s Begin with the Letter People® intervention group, or a comparison group, with all classrooms within a preschool being assigned to the same intervention condition. Fourteen schools (27 classrooms) in the study were assigned to implement the Doors to Discovery™ curriculum, 12 schools (25 classrooms) implemented Let’s Begin with the Letter People®, and six schools (27 classrooms) were assigned to the comparison condition. In a second stage of random assignment, those schools assigned to Doors to Discovery™ and Let’s Begin with the Letter People® were randomly assigned (within each curriculum) to two groups: one that received mentoring, and one that did not receive mentoring. The number of children at random assignment is not provided in the article or in author queries. However, the authors indicated that the consent rate was 65% in the intervention classrooms and 55% in the comparison classrooms. The authors also noted that at random assignment, 215 study children were in intervention group classrooms, and 203 study children were in comparison classrooms. Using the consent rate and the number of study children, we estimate that the sample of children totaled 729: 324 in intervention classrooms and 405 in comparison classrooms. At baseline, 51% of children in the Head Start classrooms were Hispanic, and 38%
were African American; in the Title I classrooms, 53% of children were Hispanic, and 27%
were Caucasian; and in the non-Title I programs, 71% of children were Caucasian, and 15%
were categorized as Other. Pretest data were collected prior to the implementation of the curriculum, and posttest data were collected at the end of the school year. The analysis sample
for the Doors to Discovery™ study included 365 children (183 Doors to Discovery™ and 182
comparison).Although the Assel et al. (2007) study used a randomized controlled trial design to assign schools to intervention or comparison conditions, the study had high attrition at the child
level and must demonstrate baseline equivalence between the intervention and comparison
group sample of children used in the analyses of outcomes. An author query was conducted
to obtain the study data necessary to establish equivalence at baseline (i.e., unadjusted
means and standard deviations of the outcome measures for the intervention and comparison
groups). Baseline equivalence was established for outcomes in the print knowledge domain
but not for the oral language or phonological processing domains. The study also discusses
differences in child outcomes for the groups that received mentoring compared with those that
did not, but since the estimated differences are not presented in the paper, we do not present
these analyses in this intervention report.
Intervention group teachers implemented Doors to Discovery™. Eight thematic units cover topics
such as nature, friendship, communities, society, and health and present rich information. The teacher guide offers open-ended statements and questions to promote discussion. Fidelity to the curriculum was measured three times during the school year. At the first evaluation, 29% of teachers scored at high levels for curriculum fidelity (4 or 5 on a 5-point scale). By mid-year, 57% of teachers received high scores for curriculum fidelity.
A second intervention group was assigned to the Let’s Begin with the Letter People® curriculum;
the effects of this intervention on the study sample are not discussed in this report.
Comparison group teachers used nonspecific curricula, which included a variety of curriculum
materials that followed state guidelines for public preschool programs. Head Start comparison
classrooms did not use a curriculum with a specified scope or sequence.
Print knowledge was assessed with the WJ-III Letter-Word Identification subtest. For a more
detailed description of this outcome measure, see Appendix B. In addition, the study authors
assessed children in the oral language and phonological processing domains. Oral language
was assessed with the Preschool Language Scale, Fourth Edition (PLS-4) Auditory Comprehension
Subscale and the Expressive Vocabulary Test (EVT). Phonological processing was
assessed with the Developing Skill Checklist (DSC) and the Rhyming section from the WJ-III
Sound Awareness subtest. The authors did not establish baseline equivalence on the outcomes
in these domains.
Support for implementation
Intervention teachers were trained on Doors to Discovery™ by the curriculum’s publishing company
during a 4-day workshop. Training took place in small groups and included instruction in all
content areas. The mentors were senior-level trainers of the curriculum. Teachers in the mentoring
condition received help from one of three senior-level trainers of the curriculum who served
as mentors. Mentors met with teachers two times a month for about one and a half hours, providing
assistance in areas of lesson planning, curriculum components, and fidelity, among other
topics. Mentors also identified and discussed areas of improvement for individual teachers. All
teachers, regardless of mentoring condition, received three feedback sessions over the course
of the school year surrounding their implementation of the intervention.