This study investigated elementary teachers' observations of how a representative sample of achieving, average and struggling readers adapted the use of best practice comprehension strategies taught in the classroom as well as during instructional level guided reading time. A researcher-constructed strategy checklist was the instrument teachers used to observe taught strategies (Reciprocal Teaching, QAR, Text Structure, Graphic Organizer Use, and Summarization) as implemented by the achieving, average and struggling readers. The study also investigated decisions teachers made to further inform their instruction through the use of electronic journal responses. Additionally, the study examined scores from three mandated literacy assessments in a southeastern Pennsylvania school district to investigate how these assessments' reading comprehension scores aligned. The scores analyzed were from a 2010-2011 third grade cohort. The assessments were: "The Developmental Reading Inventory"--DRA 2 (Beaver & Carter, 2009), "The Pennsylvania System of School Assessment" (PSSA) (Pennsylvania Department of Education, 1990) and "Measure of Academic Progress"--MAP (Northwest Education Association, 2005). Teacher interviews measured teacher attitudes, observations and perceptions of students' strategy use during instruction and test-taking. This measure strived to elicit straight forward impressions concerning each of these assessments. Findings revealed that struggling readers had the most difficulty with independence in using research based best practice strategies. However, achieving readers had more difficulty with summarization than either of the other two representative groups of readers. Correlations showed that PSSA and MAP yielded a higher positive correlation than "DRA 2" over the time of this study. Teacher interview data revealed that teachers relied more heavily upon "DRA 2" assessment information than on the other standardized tests used throughout this study. Teacher themes centralized around the fact that with "DRA 2" results, they learn about both the reading behaviors and comprehension strengths and weakness of their students. [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.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]