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人教版新教材九年级《化学》上册,在探究灭火的原理时,设计了这样一个实验:在一只点燃的蜡烛上倒扣一只烧杯,观察蜡烛的燃烧情况(如图1)。由于实验结果学生都可料到,缺少悬念,因此实验的吸引力不大。为了增加实验的吸引力,突出实验的探索性和思考性,教学中,笔者将一只蜡烛改用两只蜡烛(一长一短)进行实验,学生由于受固有思维的影响,往往会猜想短蜡烛先熄灭,而实验事实得到了与学生猜想恰好相反的结果。在这种意想不到的实验事实面前,学生的思维很快活跃起来,收到了很好的教学效果(如图2)。
In the 9th grade “Chemistry” edition of the new edition of the People’s Education Press, when exploring the principle of fire fighting, an experiment was designed to invert a beaker on a lighted candle and observe the burning of the candle (see Figure 1). Because of the experimental results, students can expect that there is no suspense, so the experiment is less attractive. In order to increase the attractiveness of the experiment and highlight the exploratory and reflective nature of the experiment, in the teaching, the author used a candle instead of two candles (one long and one short) to conduct experiments. Students are often conjectured because of the influence of the inherent thinking. The candle was extinguished first, and the experimental facts had the opposite result as the student guessed. In the face of such unexpected experimental facts, the students’ thinking quickly became active and received good teaching results (Figure 2).