Using a Lite Applet
with a Spreadsheet or Computer Algebra System
This live image looks very similar
to the one in the preceding section except that, by changing a few of the parameters
calling the applet, we have created three new buttons that enable the user to
copy data into a spreadsheet (or a computer algebra system). In this form, the
Image_and_Cursor applet might be used in a module that would lead students to
discover how to estimate the length of a complicated curve, such as the border
between Afghanistan and Iran. If you have Excel or another spreadsheet on your
computer, you might try this:
- First move this window over to
the right side of your screen to free up one or two inches of space at the
left of the screen.
- Next launch your spreadsheet
with a blank worksheet. Position the spreadsheet at the left of the screen.
Your screen should look something like the following picture, with the spreadsheet
window peeking out from behind this browser window.
- Now mark a series of points along
the border between Afghanistan and Iran by positioning the cross hairs at
each point in turn and clicking the Mark point button.
- After you have marked a series
of points along the border, click the List points button.
- In a few seconds a new window
will appear with the coordinates of the points you marked. (If necessary,
enlarge the window so you can see the coordinates.) Move this window to the
right so that it does not obscure the spreadsheet window peeking out from
behind the browser window.
- Now highlight the data in this
window in the usual way, by clicking and dragging or by using a combination
of clicking and shift-clicking.
- The next step is to copy-and-paste
the highlighted data into the spreadsheet. The way in which this is done depends
on your operating system. You may be able to simply drag the highlighted data
into the spreadsheet, or you may have to copy it using either control-c (Windows)
or command-c (MacOS) and then paste it using either control-v (Windows) or
command-v (MacOS). You can also copy-and-paste using the right mouse button
and pop-up menu on Windows machines.
- Once you have the data in your
spreadsheet you can compute the length of each segment of your polygonal approximation
to the border. Then compute the sum of the lengths. Finally convert the length
of the border measured in pixels into either miles or kilometers, using the
scale on the map.
Border Between Afghanistan and Iran is a student-ready module using this
image and applet as we have just described.
The HTML code shown here illustrates
how the Image_and_Cursor applet is called on this page. There are just a few
changes from the applet call in the preceding section.
- The parameter display_sw
now has the value 1 to specify the inclusion of the three buttons at
the right enabling the user to record and display data. (Note: "sw"
is an abbreviation for "switch".)
- The parameter cas_sw is
set to the value 2, indicating that data should be displayed in a form
suitable for a spreadsheet. Data can also be displayed in a form suitable
for Maple or Mathematica.
- The applet width is larger to
allow room for the new buttons.
To practice using the applet in this
way, you will need to follow a procedure similar to that in the preceding section.
First, you need two brief instruction pages:
- One-sheet instructions for using
Image_and_Cursor with a spreadsheet or computer algebra system
- One-sheet instructions for this
simplest use of the Image_and_Cursor applet -- you may have already
downloaded this file when you read the previous page
Next, you need a copy of this
page. [That link will open another copy of this page in a frame that will
not include extraneous JOMA codes.] Right-click in the text of the new copy
(command-click on a Mac), select View source (or equivalent), and save
in the directory of your choice. Again, the code can be edited and saved in
the application that opened it or in an HTML editor such as Dreamweaver or Front
Page. Finally, you need the following files, and they should be placed in the
same directory as the HTML page.
Now try creating your own student
exercise with and image of your choice and a computational assignment that will
make use of Image_and_Cursor data in a spreasheet or a computer algebra system.
The next section shows how lite applets
modules without writing Java programs.