Plan for Chapter 2

This is a "guided discovery" lecture plan to teach students what the components of a URL mean.
(This was written in 1997, before the course was as large as it is today, so some parts had to be adjusted. Furthermore, web servers are becoming more sophisticated, and the days of finding "Error 404" messages seem to be quickly passing us by -- instead, one is more likely to find attractive search engines, well constructed pages, or find oneself redirected to a higher level within the site.)

Summary:

1. Props: paper folders and pages, plus a magnet or two.
2. Explaining a URL
3. Practice, and File Not Found
4. Practice, Activity

Before the lesson, paper folders are prepared to represent the course site. The folders are inside each other, and have the folder name written on the outside. The URLs for the students' course pages start with www2.gol.com/users/billp/course/, so the outermost folder has "users" written on it. Inside that folder is one titled "billp", and inside "billp" are two folders ("students" and "course").
Inside the "course" folder are papers representing each page of the students' course. Each paper has a page name written on it (e.g. ch1p1.html, ch1p2.html, etc.).

Class procedures: explaining a URL.
On the whiteboard, write out the URL of a lesson page the students have already done. Let's use this as an example:

http://www2.gol.com/users/billp/course/ch1p9.html

Breaking it down into explainable bits (some of the following are instructions, and others are suggested paraphrases of what to tell students):

• http://
  All World Wide Web pages start with this. There are other kinds (like ftp://), but we don't care about them right now.
• www2.gol.com
  This is like a filing cabinet. It is the name and address of a large computer. This computer is called a "server".
• users
  Show the folders (remember, all of the prepared folders are inside "users" at this point). Inside the "filing cabinet" called www2.gol.com, there are many different folders. One is called "users". The people who pay this company each have their own folder.
• Put the folder on the white board marker tray so that it is visible.
• billp
  Take the "billp" folder out of the "users" folder and hold it up. Bill Pellowe pays this company, and his folder is called "billp". Put the folder next to the "users" folder on the marker tray.
• explaining the /
  Point out that the slash shows a division. Draw a slash between the "users" folder and the "billp" folder. Ask students to look at the URL on the board, look at the folders, and guess: What do you think the next folder will be called?
• course
  The students should have been able to guess that the next folder you'd show would be entitled "course". (Leave the "students" folder inside "billp" for now.) Hold up the "course" folder and tell them that all of their course pages are inside the folder.
• ch1p9.html
  Take out the "ch1p9.html" paper. Use a magnet or tape to attach the page to the whiteboard. Pages are inside the folder, and pages generally end in "dot html" or "dot htm".

Class procedures: Practice, and File Not Found

• Carry the course folder around the room, and give each student (or each pair of students) a page from the folder that represents a page they've already seen. (Don't use the "ch2p1.html" page yet.) Ask them to type the URL for that page into their browser.
• File Not Found
  When done, collect the pages. Ask a student to come up and look inside the folder for, say, "ch1p19.html". (Choose one which does not exist.) When they say they can't find it, repeat that to the class as a whole. She can't find it because there isn't one.
• So, what happens when you type "ch1p19.html" in with the URL? Have the students type it in. They'll get the "File Not Found" message. They should be able to realize what this means now.

Class procedures: practice and activity.

• Take out the "ch2p1.html" page. Ask the students to type in that URL.
• This brings you to the lesson page. Go through this as a group.
• The first "you try" will bring the students to the index page of the "course" folder. Tell them that if a folder has a page called "index.html", you will see the page.
• At the time this lesson is to be given, I'm not going to have an index page inside the "students" folder. Deviating from the lesson page, I'll take the "students" folder out of the "billp" folder. The students will type in the URL for that folder, and I'll explain that there is no index page, so they simply see the contents of the folder listed.
• The next step on the lesson page has the students "delete up" to my homepage.
• An interesting deviation at this point is to ask the students to try typing their own names in in place of "billp", or "bill". They should try both first names and last names. If it says "index of name", that means there is a person paying that server for Internet access, but they don't have a homepage. There are a few homepages corresponding to some of my students' names.