科学教学计《食物链》.doc

《食物链》教学设计 【教学内容 义务教育课程标准实验教科书（粤教科技版）科学六年级上册第7课《食物链》。 【教材分析】 本课选自义务教育课程标准实验教科书（粤教科技版）科学六年级上册第二单元《生物与环境》中的内容，此单元主要引领学生从不同的角度来探讨生物的生存与环境之间的关系，本课内容就是在研究了植物适应环境的特性、了解了植物对环境的依赖性及不同环境里生存着的不同生物的基础上，以一个典型的生物群落为例研究生物群落之间的相互影响，并重点研究食物链，为后面认识生态平衡、环境保护做铺垫。 【设计理念】 《食物链》是一节建构科学概念，发展学生思维的课。在本课教学中，学生经历“初步感知食物链——建立食物联系——建构食物链概念——完善食物链认识寻找、发现建立食物联系交流、分析建构食物链概念归纳、整理完善食物链认识寻找、发现建立食物联系交流、分析建构食物链概念归纳、整理——完善食物链认识 the same direction of rotation 90 ° or 180 ° for; after each disc rotor when measuring position alignment of the two half coupling constant, should also be in terms of accuracy and consistency. Surface deviation measurement, must in every 180 degrees corresponding to the two radii are equal to each other in order to eliminate errors caused by movement of the rotor. Only a support bearing of the rotor, WA couplings, such as the use of temporary leave the Center, should pay attention to keep the rotor in the measuring process in the center of the bearing oil retaining the nest does not change. Steam oil block, there should be sufficient clearance between the rotor and, in rotors make sure rotor is not on the block or seal oil. At the time of measurement, connections are not allowed between two rotors, each in a free State. Not allowed in case of assembled sleeve, Center work on the toothed coupling. Coupling tool should have adequate stiffness, installation must be secure and reliable. Coupling Center using a dial indicator, the table should be put in prison and avoid touching, to ensure correct measurement. Coupling disc after a week to return to the original position, circumference of dial gauge reading should be able to go back to the original value. When measuring the clearance of end, into the feeler of the gap should not exceed four at a time, when the gap is too large, you can use the gasket with the feeler gauge measurement of gauge blocks or finishing. bearing surface, markup should be in accordance with the mounting support pads, and retest the thickness. Once the li