知識結構即代表著概念的組織交結形式，亦可視同為某種形式的心理模式或基模。本研究使路徑蒐尋技術測量三年級學生的自然科學知識結構。樣本分高、中、低成就組，分別取自三班，含專家對照組共45人，以該校自然科學課程中的二天單元作為施測範圍。結果顯示：專家組的知識結構較有系統，而中低成就組學生則多半呈現混亂的概念組織方式；其次，自量化指數的分析也顯示，高成就組學生的PFC、PRX、GTD指數都高於中、低成就組學生。最後，研究中利用徑路圖，進行學生的錯誤概念分析，發現中、低成就組學生在此二單元中，錯誤概念多於高成就組學生。顯見錯誤概念確實是造成學童科學學習時的重要障礙。

This study examined the scientific knowledge structure of 3th grade students by using Pathfinder. The results indicated the knowledge structure of an expert group is more organized than amid-or low achievement group. In addition, the indexes of PFC, PRX and GTD also revealed that a high achievement group is higher than a mid-or low achievement group. Furthermore, we analyzed student misconceptions about these two topics by using Pfnet. The finding suggested misconceptions of mid-and low achievement groups are greater than with the high achievement group. Therefore, misconception is the main barrier for learning scientific knowledge.