.《钉子板上的多边形》ppt课件 小学五年级数学上册 苏教版.doc

8.4《钉子板上的多边形》ppt课件 小学五年级数学上册 苏教版 第8单元 用字母表示数 4 钉子板上 的多边形 学习目标 1.使学生在操作、观察、猜测、验证等活动中，发 现在钉子板上围出的多边形与它的边所经过的钉子 数，以及多边形内部钉子数的关系，会用含有字母 的式子表示发现的规律。 2.使学生在探索规律、发现规律和表达规律的过程 中，进一步感受数学抽象的意义，培养比较、分析 和简单推理的能力，增强发现问题、提出问题的意 识，积累数学活动经验。 复习导入 复习导入 复习导入 引出问题 ● ● ● ● ● ● 数一数，下面图形的面积？ 1㎝ ● ● ● ● ● ● ● ● ● ● ● ● ● ● 1㎝ ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ?● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● 引出问题 1厘米 厘 米 数一数，下面图形的面积？ 1 引出问题 1厘米 厘 米 数一数，下面图形的面积？ 1 ? ? ? ? 激活猜想 ● ● ● ● ● ● ● ● ● ● ● ● 1㎝ ● ● ● ● ● ● 1、 ㎝ ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● 、 ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ② ● ● ● ● ③ ● ● ● ● ④ ● ● ● ● 图形编号 多边形的面积/平 方厘米 多边形边上的钉子 数/枚 2 3 3.5 4 ④ 4 6 7 8 激活猜想 图形编号 S=n÷2 多边形的面积 多边形边上的 /平方厘米 (s) 钉子数/枚 (n) 2 3 3.5 4 6 7 4 8 数学是研究千变万化中不变的规律 ——开普勒 进行验证 1㎝ ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● 1㎝ ● ● ● ● ● ● ● ● ● ● 、 ● 、 ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● n=10 s=6 ● ● ● ● ● ● ● ● n=9 s=5.5 ● ● 1