K-12 online schools are proliferating in the United States. While there are some teacher preparation programs geared towards K-12 online learning, the vast majority of K-12 virtual teachers are learning on the job. Research is still emerging in this field, and additional research is necessary in this dynamic field of education. Opponents of online education cite the failure of online virtual schools to meet the federal and state proficiency standards. However, there are specific techniques being implemented in virtual schools that have resulted in some virtual online schools demonstrating academic proficiency comparable to their brick-and-mortar counterparts. This phenomenological study aimed to determine differentiated instructional practices utilized by virtual teachers as reported by virtual teacher trainers and administrators. The researchers interviewed virtual teacher trainers with experience observing virtual teacher synchronous instruction. The interviews were coded to identify themes. The data was analyzed to determine what knowledgeable observers perceived as effective differentiated instructional practices in the K-12 educational setting. The results of this study intended to support and strengthen current research on effective virtual teaching competencies. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]