This study was conducted to determine whether the traditional classroom approach to instruction involving the addition and subtraction of number facts (digits 0-6) is more or less effective than the traditional classroom approach plus a commercially-prepared computer game. A pretest-posttest control group design was used with two groups of first grade students--N=15 for the experimental group and N=14 for the control group--and their relative gains in achievement were compared. The computer game used by the experimental group in addition to regular classroom instruction was Alligator Mix, which is designed to help students increase their skills in both adding and subtracting numbers 0-9 by feeding alligators in the swamp. Since the game has the ability to establish increasingly more difficult levels for mastery, students are required to memorize and recall the number facts without stopping to determine the answers. The study lasted 20 school days and a t-test was used to measure the significance of difference between the mean gains of the two groups. Six data tables display the findings of the study, and conclusions indicate there were no significant differences between the experimental and control group in mathematical gains involving the addition and subtraction of number facts; however, both groups did show significant gain. Recommendations for future study and a list of 32 references complete the document. (JB)