本研究旨在發展「生物恆定性二段式診斷測驗（TTDTH）」以診斷國中學生在「生物恆定性」所存有的另有概念。研究工具TTDTH 共20 個選擇題，試題的第一部份為命題陳述，第二部份為選答前一選項的原因，題目先由學科專家審題後施測。預試分析顯示，題目的平均難度與鑑別度值分別是0.47 及0.59，信度值則是0.81。完成的工具施測920 個七年級學生以探討學生在生物恆定性概念的現況。資料分析結果顯示，國中學生在恆定性定義、體溫來源、內外溫動物的差異、體溫的調節機制、呼吸與呼吸運動、氣體調節機制、水分調節機制、血糖及血糖的調節機制等的想法有別於課程中所教授的概念。

The purpose of this study was to develop a two-tier diagnostic instrument–Two-Tier Diagnostic Test for Homeostasis (TTDTH) to find juniors’ alternative conceptions of homeostasis. None-hundred twenty students were sampled from six junior high schools in the middle of Taiwan. These students were administered the TTDTH. The results showed that the average difficulty and average index of discrimination of the TTDTH were 0.47 and 0.59 respectively. The Cronbach alpha value for internal consistency was 0.81. Even though the students had received instruction in biology classrooms, 7-9th grade students still had alternative conceptions about the definition of homeostasis, source of body temperature, difference between endothermic animal and poikilothermic animals, homeostasis mechanism of body temperature, difference between respiration and respiratory movement, homeostasis mechanism for gases, accumulation and depletion of the water, homeostasis mechanism for water, importance of blood sugar, source of blood sugar and the homeostasis mechanism of blood sugar. Findings of this study suggested that the TTDTH could be used as a diagnostic test for homeostasis. The identification of alternative homeostasis conceptions can be a valuable resource for diagnosis of students and for instruction and curriculum development related to homeostasis.