This research investigation examined the effects of Singapore's Model Method, also known as "model drawing" or "bar modeling" on the word problem-solving performance of American third and fourth grade students. Employing a single-case design, a researcher-designed teaching intervention was delivered to a child in third grade over the course of 8 teaching sessions. Using researcher-designed assessment probes, repeated measures of the dependent variable (percentage of problems solved correctly) were taken through three different phases: baseline, intervention, and maintenance. The design was repeated across four different third and fourth grade participants. The results demonstrated the existence of a positive functional relationship between the independent variable (the model drawing intervention) and the participant's problem-solving performance. The percentage of problems solved correctly rose significantly as soon as the intervention phase began and the child employed Singapore's Model Method in solving complex word problems. The pattern was repeated across two different problem types, multiplicative comparison word problems and fraction word problems. The validity of the findings was strengthened considerably when the results showed a very similar functional relationship across four different subjects in grades 3 and 4. The existence of a functional relationship between model drawing and word problem performance has implications for research, policy and teaching practice in elementary mathematics education. Limitations of this study as well as implications will also be discussed. [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.]