在上第八册养蝌蚪一课时,我让学生按照书上讲的方法去养蝌蚪,屡次失败。后来我到池塘边、稻田边去观察蝌蚪,发现小蝌蚪的发育不是仅有受精卵就可以,还与受精卵所在的,水源、地势、阳光都有关系,这说明蛙在排放受精卵前是经过精心选择的,该地方适应小蝌蚪的生长,且有供它发育所需的养料。而我们在养殖的过程中经常换水,换泥土,是不是因此使蝌蚪不能正常生长发育呢? In the eighth book tadpole raising a class, I let the students talk in accordance with the book to raise tadpoles, repeatedly failed. Then I went to the pond side of the tadpoles to observe the rice fields and found that the development of small tadpoles is not only the fertilized eggs can, but also with fertilized eggs where the water, topography, sunshine have a relationship, indicating that frogs before the release of fertilized eggs is After careful selection, this place accommodates the growth of small tadpoles and has the nutrients needed for its development. And we often change the process of farming water, change the soil, is not so tadpoles can not grow normally?