Archive for February, 2011

Screencasting the easy way

Hi all,

I just discovered a new tool for creating screencasts! Screencasts are the video clips I’ve included in previous posts that show some or all of your computer screen while also recording narration. So far I’ve been using Jing and to create these which has worked wonderfully so far.

The other day however, while looking for another tool, I came across another excellent way to create screencasts without having to download any software or sign up for an account. To create your screencast:

  1.  Make sure you have something interesting on the computer screen to demonstrate and a microphone plugged in… 🙂
  2. Point your web browser to and click on the “Start Recording” button. (Say yes if it asks you for permission.
  3. Stretch the box that appears over the section of your screen that you’d like to demo.
  4. Press Record

Once you’re finished, return to the screencast-o-matic browser window and select what you would like to do with the video – including upload to screencast-o-matic, youtube, or download to your computer. If you choose to download the video the software gives you the option of three different formats:

  • mp4 – Good for importing into iMovie
  • avi – Good for importing into Windows Movie Maker
  • flv – Good for importing into Moodle

The free version of Screencast-o-matic (SOM) gives you up to 15 min per video – which is plenty for a tutorial. Remember you’ll want people to view it 🙂

Feel free to share your own screencasts in the comments below.


February 28, 2011 at 3:24 pm Leave a comment

A center by any other name… Geogebra at work

Recently I was asked how one finds the center of a scalene triangle. There are in fact four possible answers to this question. Below I’ve recorded 5 screencasts on how to use Geogebra to investigate the properties of each type:

  1. Properties of an incenter (the intersection of the three angle bisectors).
  2. Properties of a circumcenter (the intersection of the three perpendicular bisectors).
  3. Properties of a centroid (the intersection of the three segments connecting each vertex with the opposite bisector).
  4. Properties of an orthocenter (the intersection of the three altitudes).
  5. Releationships between the four centers.

February 6, 2011 at 7:19 pm Leave a comment


February 2011
« Jan   Mar »