Sunday, April 10, 2011

Random Group Generator Update

This morning I was able to finish an update for the Random Group Generator. Now you can choose to divide the groups based on the number of groups you want or the maximum size of each group.

First select the mode, then enter the size larger than 1. If you selected max group size then you have the choice between two modes: maximum group size and balanced group size.

The maximum mode makes sure that every group is filed to capacity before filling the next group.  For example if you have 16 students and wanted a maximum of 6 students per group. There would be 2 groups of 6 and 1 groups of 4.

The balanced mode makes sure that the group size fairly equal in size. For example if you have 16 students and wanted a maximum of 6 students per group. There would be 1 group of 6 and 2 groups of 5.

Friday, April 1, 2011

Color wheel in the classroom.

In science class we are studying about light and color. The video clips below demonstrate a simple way for students to experiment with different ways to create color and how they mix together. The first demonstration used Inkscape ( and allows the student to mix the colors to create new colors whereas the second video uses Gimp ( and has the computer mix the colors for you using layer modes of addition and subtraction.

Inkscape Color Wheel:
If students have been introduced to Inkscape and follow the process shown in the video it should take about 10 minutes to finish.

Here is a basic outline of the steps.

  1. Create a circle.
  2. Change the color to red.
  3. Select the circle and duplicate it (ctl-d), then move it to the right so that the two circles overlap.
  4. Change the color of the new circle to green.
  5. Select the new circle and duplicate it (ctl-d), then move it down so that all three circles overlap.
  6. Chance the color of the new circle to blue.

    Now you should have the three primary colors red, green, and blue.
  7. Select all (ctl-a) of the circles and duplicate (ctrl-d) them twice.
  8. Select to of the circle the red and green circles, by clicking the first circle red circle and pressing shift to select the green circle, with both circles selected select intersection from the paths menu. Now you should have a new shape similar to that of a football. If you can't see it raise it to the top. 
  9. Next change the color mixture to have all red and all green.
  10. Repeat the process for both of the other overlaps. 
  11. Lower the circles you create to the back if necessary.
  12. Now select the three football like shapes in the center and duplicate them. 
  13. With the shapes still selected again select intersection from the paths menu. 
  14. Now change the color to have red, green, and blue values set to full on.
Now you have a color wheel.

I thought that this exercise was pretty cool but the computer can also do it by itself. Check out the activity using Gimp shown below.

Gimp Color Wheel:

You should be able to duplicate the Inkscape activity using other vector drawing programs like Adobe Illustrator.
You should be able to duplicate the Gimp activity using Adobe Photoshop or any other program that has layers with modes of addition and subtraction.

Note that both Inkscape and Gimp are available for Windows, Mac, & Linux platforms.