The purpose of this study was to compare a teacher-centered explanatory instruction with a monitoring-focused instruction from the viewpoint of motivation types and learning strategies in second grader students of middle school. The biology achievement from pre-instruction and post-instruction differred significantly in each groups (p=.000). In the instructional effect on biology achievement, monitoring-focused instruction was more effective than explanatory instuction. From the statistical analysis of covariance, however, the difference of instructional effects between these groups was not significant. From the result of regression analysis, the ego-orientation made a negative effect on the biology achievement in monitoring-focused instruction. In the influence of learning strategies on biology achievement, monitoring strategy made a significantly positive effect in monitoring-focused instruction, which was the same as our intended instructional plan. Memorization strategy made a significantly positive effect in explanatory instruction. Organization strategy was effective positively in both groups. These results showed that the regression analysis of effective factors on biology achievement was similar with the group patterns of preference for motivation and learning strategies.