知识点四：在线学习

4．Online Learning 在线学习

4.1 What is online learning?

    Online Learning (also called electronic learning ,or e-learning) is the result of instruction that is delivered electronically using computers and computers and computer-based media.The material are often accessed through a network.Sources include websites,the Internet,intranets,CD-ROMs, and DVDs. In addition to delivering instruction,e-learning can monitor learner performance and report learner progress. E-learning is not accessing information (e.g.,Web pages), but guiding learners to specific outcomes (e.g.,objectives).

图7.22   数控加工编程室

(1) Advantages

• Variety of media 多样化的媒体：因特网是将信息传递给世界各地的学习者的通用手段。
• Up-to-date information 最新的消息：扩展了小学校、农村学校以及在家中接受教育的学习者的视野。
• Navigation 导航：因特网的主要优势就是在文件内和文件之间进行浏览的能力。
• Idea exchange 观点的交流：学生们可以与页顶研究领域的专家进行“会话”。
• Convenient communication 便利的交流。
• Low cost 低成本：硬件、软件、电话以及电信服务的费用很少，并且还在不断降低。

(2)  Limitations

• Age-inapproptiate 不适合某些年龄阶段的材料：在因特网中，儿童喜欢的游戏和音乐中经常伴随着烟草和酒水的广告。学生很容易接触到对他们来说难以理解或者过于成人化的话题。
• Copyright 版权问题：因为在网络中信息的获得十分便利，个人能很方便、快速地下载文件，稍微修改，以一种在法律上不太妥当的方式使用。学生上交的论文和项目很可能不是他们自己的作品。
• Unprecedented growth 空前的发展：据估算，每天大约有几千个新的站点加入到因特网中。这样的增长速度使我们找到想要的信息变得相当困难。
• Support 支持：良好的技术支持非常重要。
• Access 访问：无论是通过有线网络、无线系统还是调制解调器，所有的使用者必须有连接网络的技术手段。
• Access speed 访问速度。
• Lack of quality control 缺乏质量控制：使用者必须是一个“批判性思维者”，是一个能够评价信息的读者。

(3)  Integration

    Whole courses and programs of study are available through online learning.Students can access courses that might not be available to them at their school. Students can advanced placement classes from other high school or from colleges and universities anywhere in the world.

    There are issues that need to be addressed by anyone wishing to venture into this area of academic study.First is the credentials of the institution offering the degree.Another is the issue of the quality and rigor of the courses.Finally,there are issues related to costs associated with online courses,such as the equipment requirements,online charges and tuition.

    E-mail can be integrated into lessons and used by students to gather information from,and ask questions of,individuals beyond the school walls(e.g.,other students and experts).Students can also use e-mail to gather information for individual projects.

    One growing use of e-learning at the P-12 level promotes writing skills by connecting students with “electronic pen pals” or “key pals”.

    Systerms have also been set up that allow student from diffent countries,even those speaking different languages,to learn about each other’s cultures through computers mediated communication.

4.2 Network 网络

(1)  Local Area Network (LAN) （局域网）

    The simplest of all networks is a Local Area Network (LAN). A LAN connects computers within a limites area,normally a building,office, or laboratory.These networks connect individual computers to one another to permit exchange of files and other resourses

图7.23   计算机机房的典型局域网

    A single computer, generally located in the office or media center,can serve as an entire school’s file server.Through a LAN ,all of the classrooms In a school can have access to the school’s collection of software.

(2)  Wide Area Network (WAN) （广域网）

    Networks that extend beyond the walls of a room or building are called Wide Area Network (WAN). In this arrangement,the buildings are linkes to a centralized computer that serves as the host for all the software used in common.

    It often connects the buildings within a school system or on a college campus.

(3)  Wireless Network （无线网）

    Wireless Network connects computers without wire. Such networks use transmitters placed inside the room,throughout the building,or across campus and operate in the same manner as hardwared networks.

    Computers are also no longer bound to workstations.Laptops may be used anywhere within the room,building, or campus.

(4)  The Internet （因特网）

    The Internet is a worldwide systerm for linking smaller computer networks together.It is a network of networks with a frequently changing collection of millions of computer networks serving tens of millionsof people around the world.

图7.24   因特网——计算机网络的集合

图7.25   在家里或者教室里享受因特网服务

(5)  The World Wide Web （万维网）

    The World Wide Web is a network of networks that allows you to access,view,and maintain documents that can include text,data,sound,and video.

    To use the Web for online learning,Web pages have to be designed and written,and a host computer must be identified to house them.Universities and large companies are usually directly cennected to the Interner and run the necessary Web hosting(server) software.

(6)  Intranets （内部互联网）

    A special type of network,called an intranet,is not used by the general public,but by corporations and large organizations.Intranets provide internal networks for companies or schools.Intranets are a way of increasing communication,collaboration,and information dissemination within companies or schools where divisions,departments,and workgroups each use a different computer platform(hareware and / or operating system),or where users work in geographically distant locations.

图7.26   防火墙保护内部互联网不受外部用户的干扰，但允许内部用户访问外部网络

(7)  The Advantages

• Ease of communication 通信的便利；
• Sharing hardware 共享硬件设备；
• Centralization 集中性：员工或学生可以随时访问存储在中央数据库中的信息；
• Consistency 一致性：由于信息的集中储存，所有群体都可以浏览到同一版本的教育资源 ;
• Currency 更新及时。

(8)  The Limitations

• Cost 成本高；
• Requires special network-compatible software 需要专门的网络兼容软件；
• Limited number of users 有限的用户数：如果没有额外的设备，用户很可能要等待，轮流使用这些网络设备；
• Unreliable remote connections 不可靠的远距离链接；
• Speed of response 响应速度。

（9） Integration

        利用网络开展在线学习的一个实例是一个有 15 — 20 台联网计算机组成的实验教室。当教师希望每个学生都能在课程中使用计算机学习的时候，实验室为全班同学提供了同时使用计算机的可能。网络中的软件和数据文件可以存储在方便的位置。当所有的计算机防止在同一个房间里时，监督和安全保护便很容易做到。 在一个计算机实验室里上课的另一种应用是教师可以锁定学生的屏幕和、或键盘，让学生集中注意力听教师的讲述。