简介:摘要初中生物课内容庞杂,知识点繁多,但教学时间有限。怎样才能在有限的时间内,将学习目标落实好,完成预期的目标任务呢?唯一的方法就是“高效课堂”,即以新课程理念为指导,遵循教学规律、教学原则和学科特点,运用有效的教学手段,以尽可能少的时间,实现课堂教学效益的最大化。
简介:Ifyoulookatthenightsky,you'lloftenseestarsmovingveryquickly.Infact,theymovemuchmorequicklythantheyshould,accordingtotheirsizeandthelawsofphysics.Scientistsdonotcompletelyunderstandwhythespeedofthesestarsissohigh.Butmanybelievethereasonisbecausemuchoftheuniverseismadeofsomethingcalled"darkmatter."Groupsofstarscalledgalaxies[星系],suchastheMilkyWay,mightevenconsistof90%darkmatter.