Date on Master's Thesis/Doctoral Dissertation


Document Type

Doctoral Dissertation

Degree Name

Ph. D.

Department (Legacy)

Department of Teaching and Learning

Committee Chair

Bauder, Debra K.

Author's Keywords

Vocabulary; Mathematics; Constant time delay; Non-verbal; Moderate and severe; Communication competency


Children with disabilities--Education (Secondary); Vocabulary--Study and teaching (Secondary); Mathematics--Study and teaching (Secondary)


Constant Time Delay (CST) has been used extensively as a procedure to teach children with disabilities a variety of skills. There is a preponderance of evidence that this instructional strategy is a highly effective (Handen & Zane, 1987; Koscinski & Gast, 1993; & Schuster, Stevens, & Doak, 1990). However, there appears to be a lack of research regarding the use of CTD with children with moderate and/or severe disabilities in learning core content vocabulary. Therefore, the primary purpose of this study was to determine if students with moderate and severe disabilities could acquire core mathematical vocabulary content through the use of constant time delay (CTD) procedures. This study examined the ability of 10th graders with moderate and severe disabilities to acquire core content Geometry terms using constant time delay instruction. The investigation included six participants who were divided into two groups, a verbal group and a non-verbal group. All six participants qualified to participate in the state's alternate assessment. A single subject multiple probe baseline experimental research design was used. The results of this study were mixed. The verbal participants were able to reach criteria using CTD procedures. It should be noted the verbal group's research design was the multiple probe baseline research design. However, the nonverbal group was unsuccessful in reaching criteria through a multiple probe baseline design. Therefore, case studies of these students were conducted. The participants from the nonverbal group were unable to reach criterion on any of the vocabulary words. The lack of reaching criterion might be due to several factors including the lack of verbal skills and/or having the prerequisite skills needed to participate in the instructional procedure. Therefore, procedural changes might be in order before replication of this study can be completed. Analysis of the data indicates that additional studies are needed to determine if and to what degree the verbal status a participant has on acquisition of core content using CTD. Further research regarding skill and academic acquisition for children who are non-verbal is warranted based on these findings.