Many students at the elementary level grapple with problem solving in mathematics, and low success in mathematics is prevalent in elementary schools in The Bahamas. The purpose of this concurrent mixed methods study was to determine the degree that 12 teachers, from 4 public elementary schools in 3 districts are currently using constructivist strategies during mathematics instruction and its impact on student learning. Analysis of the classroom observational data determined that the teachers fell into two groups, which were seldom use of constructivist strategies and moderate use of constructivist strategies. The other phase of the study was to determine the degree of constructivist strategies used by teachers in the classroom on students' mathematics achievement. Third and sixth grade students of the teachers in the two groups participated in a pre and post test called the Grade Level Assessment Test. "T" test results indicated no significant difference in student achievement for 3rd graders; for 6th grade students, the students of teachers who seldom used constructivist strategies demonstrated higher growth than the students in the moderate constructivist group. Recommendations were made to increase professional learning and support to increase teachers' effective use of constructivist strategies and conduct follow-up studies to better understand the impact of teachers' practices on student achievement. The results of this study promoted positive social change by raising awareness and adding to the body of literature regarding the degree that some teachers are using constructivist strategies or not using them in the classroom setting and the impact this is having on students' mathematics achievement. School leaders can use the results and literature review from this study to make informed decisions about professional learning in order to increase student achievement in mathematics. [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.]