資優低成就學生是資源的浪費，要掌握此議題，必須先探討三個問題。一、低成就學生的出現率為何？不了解出現率，將無法評估與追蹤問題的嚴重性；二、低成就出現率與篩選方式有直接的關係，但什麼是相對較佳的方式呢？三、許多低成就學生的輔導策略，都未考慮低成就者的類型，難道數學低成就只有一種類型嗎？本研究從雙北市抽取3,312位七年級學生為對象來探討以上三個問題。結果發現：一、數學資優低成就學生的出現率為11.4%，比國外大多文獻所報告來得低；二、分析後建議採用「綜合法」是相對較佳的分類法；三、本研究將數學低成就學生區分為：臨界型、完美主義型、普遍型、焦慮型與習得無助型等五種低成就類型，文末對數學低成就的議題提出相關建議。

Underachiever has been described as “one of the greatest social wastes” in Taiwan. To investigate this issue, three essential questions regarding underachievement were elaborated: First, what was the incidence of underachievers on math? Second, since the incidence of underachievers varied with the methods to identify them, which one would be the best way? Third, many literatures were discussing how to help and provide necessary counsel to underachievers without considering the types of them. Therefore, were there different types of underachievers? Was there only one type of underachievers? The data of the study was based on a sample of 3,312 students studying the 7th grade from junior high schools in Northern Taiwan. The results were as follows: (1) The incidence for underachievers was 11.4%, that was far less than the reports from the western literatures. (2) It was proposed that the integrated method was the better method to identify the underachievers from the achievers. (3) Five types of underachievers on math were identified: Borderline, Perfectionism, Average, Anxiety and Hopelessness by applying latent profile analysis. Based on the findings of this study, pedagogical implications for underachievement were discussed and provided for underachievers of math.