Recent reports indicate that although 17-year-old high school students know some basic addition and subtraction facts, few of the students are capable of solving multi-step mathematics problems. A non-equivalent pretest-posttest control group design study examined the effects of a teaching method emphasizing manipulative use on the mathematics achievement of third-grade students. Two third-grade classes with 26 students each were selected to participate in the study. Reported demographic data indicated that the control group class from western Iredell County was composed of 10 (38%) white male students, 3 (12%) black female students, and 13 (50%) white male students, and that the experimental group class from southern Iredell County was composed of 10 (38%) white male students and 16 (62%) white female students. A 2-week geometry unit from the Silver Burdett textbook was administered in both classes. The experimental group teacher used mathematics manipulatives to teach the concepts presented in the unit, and the control group teacher used only drawings and diagrams to teach concepts. Analysis of covariance revealed that the experimental group using mathematics manipulatives scored significantly higher in mathematics achievement on the posttest scores than the control group. Further study is recommended to see if this finding is generalizable beyond the two classes studied or the subject of geometry. The pretest and the posttest are attached. (MDH)