"Don"t you be too sure, little girl," said Fred. "You had better wait a bit.""Even then," said Will, "I couldn"t make out how we were going to get any nearer to it with that cork and the basin of water.""Oh, do tell me all about it," said Norah. "I don"t like puzzles.""Well then," said Fred, "teacher held a cork at the bottom of the bowl of water, and then let go.""Yes," said Norah, "and of course the cork rose to the top of the water.""Ah, but why did it rise?" asked Fred. "Would a stone rise?""The cork rose," said Norah, "because it is lighter than the water; the water pushed it up. The stone is heavier than the water and sinks to the bottom." "That was all teacher wanted us to see," said Fred, "and then he went back to the balloon. You remember seeing the men send the balloon up in the park last summer. It roseup through the air as easily as the cork rose through the water. What does that prove?""I suppose," said Norah, "it proves that the balloon is lighter than the air. But I can"t see how that can be, for there was a car hanging from it, and there were two men in the car.""Well, it certainly was lighter than the air," said Fred, "or it would never have risen and floated away as we saw it. Let us find out what made it light.
同类推荐
校园科普类活动指导手册
根据党和政府有关政策和部门的要求以及国内外最新校园文化艺术的发展方向,特别编撰了《五彩校园文化艺术活动》丛书,不仅包括校园文化艺术活动的组织管理、策划方案等指导性内容,还包括阅读、科普、歌咏、器乐、绘画、书法、美化、舞蹈、文学、口才、曲艺、戏剧、表演、游艺、游戏、智力、收藏、棋艺、牌技、旅游、健身等具体活动项目,还包括节庆、会展、行为、环保、场馆等不同情景的活动开展形式等,具有很强的系统性、娱乐性、指导性和实用性。中学文科课程资源-诗中山
诗词是阐述心灵的文学艺术,而诗人、词人则需要掌握成熟的艺术技巧,并按照严格韵律要求,用凝练的语言、绵密的章法、充沛的情感以及丰富的意象来高度集中地表现社会生活和人类精神世界。中国诗起源于先秦,鼎盛于唐代。中国词起源于隋唐,流行于宋代。中学化学课程资源丛书-化学天天见
作为科学教育的重要组成部分,新的化学课程倡导从学生素质的培养和社会发展的需要出发,发挥学科自身的优势,将科学探究作为课程改革的突破口,激发学生的主动性和创新意识,促使学生积极主动地去学习,使获得化学知识和技能的过程也成为理解化学、进行科学探究、联系社会生活实际和形成科学价值观的过程。本套丛书集知识性与实用性于一体,是学生在学习化学知识及教师在进行引导的过程中不可或缺的一套实用工具书。
热门推荐
唯爱柠檬布丁校草你别闹
“跟我走。”林熙泽说到。“我不要!”檬檬哽咽的说,转身跑开了。“檬檬,檬檬......”林熙泽追上去一把拽过檬檬,摁在他的怀里,说“对不起,檬檬。”檬檬一把推开他,说“你给我滚,我不要再见到你,走开,走啊......”//吶吶吶演讲的艺术(经典励志文丛)
拥有演讲口才的能力,是一个人成名、成功的快捷途径!本书使你的收入增加,学会怎样有效力的讲话,获得成为领导者的资格!本书不是一本教您如何发出悦耳之声,如何说出优美之句的手册,而是教你如何通过建立自信来提高自己的表达能力,如何通过有效的演讲扩大自己的影响力。让你步入幸福的生活。迈向成功的职业生涯。