國中學生放學之後，寫數學作業時間成長對數學學習成就影響值得重視。本研究以基隆市國中生學習狀況資料庫，追蹤五學期1,586名學生寫數學作業時間對數學學習成績的影響，透過單因子重複量數變異數分析、迴歸分析與潛在成長模式分析獲得結論如下：國中生寫數學作業時間成長軌跡呈現直線下滑，七年級下學期寫數學作業時間最高，隨著學期往後推移，寫作業時間逐漸減少，九年級下學期最少。七年級生寫數學作業時間和九年級下學期數學學習成績沒有顯著關聯；然而國中生五學期寫數學作業時間逐漸減少，反而在九年級下學期數學學習成績提高。學生寫數學作業時間起始點與五學期寫作業時間成長幅度沒有關聯。雖然七年級下學期最高，但是與八年級上學期至九年級下學期寫數學作業時間逐漸減少沒有顯著關聯。本研究特色在於發現，國中生寫數學作業時間呈現直線減少現象，七年級下學期寫作業時間最高，在五學期寫數學作業時間逐學期減少，反而對九年級生數學學習成績愈好。這指出寫數學作業時間要愈多，數學學習成績才會好的刻板印象。本研究深入討論，提出建議。

After junior high school students are out of school, the influence of time spent doing math homework on math learning achievement de¬serves attention. This research used the Keelung City Junior High School Students’ Learning Database to track the impact of the time spent doing math homework on mathematics academic performance among 1,586 students in five semesters. Through one-factor repeated variance analysis, regression analysis, and latent growth model analysis, the following con¬clusions were obtained: The growth trajectory of junior high school stu¬dents’ math homework time showed a linear decline. The seventh grade had the highest math homework time in the next semester. As the semes¬ter gone on, the doing homework time gradually decreased, and the ninth grade was the least in the next semester. There was no correlation be-tween the math homework time of seventh graders and the next semester of ninth grade mathematics; however, the time for junior high school stu¬dents to do math homework in the fifth semester gradually decreases, but the ninth grade math performance in the next semester improves. There was no relationship between the starting point of the time for doing math homework and the growth rate of the time for doing homework in five semesters. That is to say, although the second semester of the seventh grade was the highest, it is not related to the gradual decrease in the time for doing math homework from the first semester of the eighth grade to the next semester of the ninth grade. The feature of this study was that it is found that the time spent doing math homework in junior high school students showed a linear decrease. The time for doing homework in the seventh grade was the highest in the second semester, and the time for doing math homework in the fifth semester decreased each semester. On the contrary, the mathematics learning performance of the ninth grade students were better. This broken the stereotype that you need more time to doing your math homework to get good grades. This study further dis¬cussed and made recommendations.