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一、变中求“准”出示图1中的湖泊,然后框出外围的平行四边形,问湖泊的面积大约是多少?生:用130×110。师:可以吗?生:可以。师:很可以吗?生:用平行四边形把湖泊框住了,平行四边形的面积比湖泊的面积应该大一些了。再出示图2,在湖泊里面有一个平行四边形。师:湖泊的面积大约是多少?
First, the change in seeking “quasi” to show the lake in Figure 1, and then box out the periphery of the parallelogram, asked the area of the lake is about how much? Students: with 130 × 110. Teacher: Can you? Health: Yes. Teacher: Is it okay? Students: boxed the lake with a parallelogram. The area of the parallelogram should be larger than the area of the lake. Figure 2 is presented again, with a parallelogram inside the lake. Teacher: What is the area of the lake?