「預測-觀察-解釋」策略在高中教學之應用—銅循環實驗
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2018
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本論文研究銅循環實驗的最佳化設計，以高中生為對象，設計可在高中實驗室執行的實驗步驟，並以「預測-觀察-解釋」策略 (POE 策略) 進行實驗流程的規畫，進一步探討最佳化的銅循環實驗和 POE 策略對學生的學習是否有所幫助。
銅循環實驗以 0.10 克金屬銅粉為起始物，在熱的 5% CH3COOH 溶液中 (約 90 ℃) 可被 3% H2O2 溶液進行氧化，生成藍綠色的 Cu(CH3COO)2 溶液。待冷卻後，在溶液中滴入 4 M 的 NaOH 溶液，產生藍色的 Cu(OH)2 沉澱。將沉澱浸泡在 80 ℃ 以上的熱水中，會生成黑色的 CuO 沉澱。滴入 6 M H2SO4 後，黑色沉澱消失，得到藍色的 CuSO4 溶液。利用容量瓶把 CuSO4 溶液稀釋至 10 毫升後，取出 5 毫升放入 7 毫升樣品瓶中，再加入 1 毫升的 35% N2H4 溶液，將樣品瓶浸泡在熱水中 5-10 分鐘，可見到容器壁還原生成紅色的銅鏡。
針對高中資優班學生共 58 人進行實驗課程，對照組學生 29 人，實驗組學生 29 人，皆分為 10 組。學生進行實驗操作後，講述式教學 (對照組) 學生的產率為 113 ± 29%、POE 策略 (實驗組) 學生的產率為 142 ± 44%。
在課後問卷調查中，有 77% 的學生在進行完銅循環實驗後，願意花時間進行其他實作實驗。在實驗組中，有 81% 的學生同意 POE 策略對學習動力和喜歡化學的程度有所幫助。
A safe, convenience, bench-top copper cycle has been designed for high school students. Prediction-Observation-Explanation strategy (POE) strategy was incorporated to the experimental processes to evaluate students’ operation. Copper cycle involves 5 reactions. The first reaction is copper oxidation. Place 0.10 g of copper powder in hot 5% CH3COOH solution (~ 90 ℃). The oxidation by 3% H2O2 is sufficient to give a blue-green copper acetate solution. Adding 4 M NaOH solution into the solution dropwise forms blue Cu(OH)2 precipitates. When the suspension is immersed in hot water (> 80 °C), a black CuO precipitates formed. With the addition of 6 M H2SO4, the precipitates dissolve and result a blue CuSO4 solution. Dilute the CuSO4 solution to 10 mL using a volumetric flask. Transfer 5 mL into a 7 mL vial and add 1 mL of 35% N2H4 solution. Immerse the vial in hot water for 5-10 minutes. Shining copper mirror appears on the vial’s wall. A total of 58 high school students had conducted the experiments. The control group taught by regular method had 29 students, divided into 10 groups, and the experiment group taught by POE method had 29 students, also divided into 10 groups. After the students completed the experiments, the yield of the control group was 113 ± 29%, and the POE method group was 142 ± 44%. From the questionnaire survey, 77% of the students were willing to spend time for other experiments after the copper cycle experiment. The experiment group, 81% of students agree that POE method are helpful for academic motivation and the passion for chemistry.
A safe, convenience, bench-top copper cycle has been designed for high school students. Prediction-Observation-Explanation strategy (POE) strategy was incorporated to the experimental processes to evaluate students’ operation. Copper cycle involves 5 reactions. The first reaction is copper oxidation. Place 0.10 g of copper powder in hot 5% CH3COOH solution (~ 90 ℃). The oxidation by 3% H2O2 is sufficient to give a blue-green copper acetate solution. Adding 4 M NaOH solution into the solution dropwise forms blue Cu(OH)2 precipitates. When the suspension is immersed in hot water (> 80 °C), a black CuO precipitates formed. With the addition of 6 M H2SO4, the precipitates dissolve and result a blue CuSO4 solution. Dilute the CuSO4 solution to 10 mL using a volumetric flask. Transfer 5 mL into a 7 mL vial and add 1 mL of 35% N2H4 solution. Immerse the vial in hot water for 5-10 minutes. Shining copper mirror appears on the vial’s wall. A total of 58 high school students had conducted the experiments. The control group taught by regular method had 29 students, divided into 10 groups, and the experiment group taught by POE method had 29 students, also divided into 10 groups. After the students completed the experiments, the yield of the control group was 113 ± 29%, and the POE method group was 142 ± 44%. From the questionnaire survey, 77% of the students were willing to spend time for other experiments after the copper cycle experiment. The experiment group, 81% of students agree that POE method are helpful for academic motivation and the passion for chemistry.
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銅循環實驗, 銅鏡反應, 「預測-觀察-解釋」策略, 探究與實作, copper cycle, copper mirror, Prediction-Observation-Explanation (POE) strategy, inquiry and practice