# Straightedge and compass constructions with Geogebra

## Recording

Full records (chat, video, voice).

Saturday, February 6th 2010 we met in the LearnCentral public Elluminate room at 10:30am Pacific / 1:30pm Eastern time:

Linda Stojanovska described her work with GeoGebra, focusing on straightedge and compass constructions, as well as the mathcast framework for capturing and sharing this type of content.

Linda would like to thank Maria Droujkova for arranging this presentation, for her availability for questions and for her excellent handling of the Elluminate environment. I do so like events that start on time, end on time and work in the meantime :).

I would also like to thank my bro Tim Fahlberg (the mathcast wizard) for all his help and encouragement, but particularly now for his help with Elluminate.

Website for this event: http://geogebrawiki.wikispaces.com/Compass-and-Straightedge

## Host: Linda Stojanovska

Dr. Linda Stojanovska is a professor in the Department of Computer Science and Engineering, University of St. Clement of Ohrid, Bitola, Macedonia, and a long-time computer geometry champion.

Linda's blurb:

GeoGebra is FOSS dynamic math software. Everyday I am amazed at the possibilities for learning that this software offers. Not show-and-tell, but try, explore and learn - anywhere because its free. And GeoGebra is continually being improved and users have influence.

The GeoGebra compass tool came at my suggestion. The reason? I was trying to teach my son constructions with a real compass and straightedge and kept having to erase and was tearing my paper (and my hair out). But I couldn't find any software where the techniques in the application and in real life were the same. With GeoGebra I could make my own compass tool. Then I wrote into the GeoGebra forum and the tool was added to GeoGebra.

But how to get the word out? How to show what can be done?

I won't read anything - I am an AV learner and I think many others are too. First, came a series of mathcasts - one describing the tools and then seven showing how to do the 7 basic compass and straightedge constructions with the steps corresponding exactly to real life construction. We opened the GeoGebra channel on YouTube and a playlist for Compass & Straightedge with GeoGebra and these mathcasts are available in HD and captioned (see above).

Second, some webpages with still images and GeoGebra worksheets. GeoGebra worksheets can be embedded in almost any wiki (see below). They are interactive worksheets so you can work on them online - even on a school LAN. No download or installation required. Or you can download and work offline without internet.

#1 Construction - Copy a line segment
- Given a line segment AB and a line with a point P on it. Construct a line segment PS on the line that is congruent to AB.
Interact in the worksheet by clicking and dragging any blue point. You can watch the construction by clicking on Play. You can delete everything and make your own construction. And - if you have GeoGebra - you can double-click and save your changes to your computer.
Sorry, the GeoGebra Applet could not be started. Please make sure that Java 1.4.2 (or later) is installed and active in your browser (Click here to install Java now)

You can embed animated GeoGebra files in Wikispaces. Click on the Play button (bottom left) or click & drag the slider s. Resource
Sorry, the GeoGebra Applet could not be started. Please make sure that Java 1.4.2 (or later) is installed and active in your browser (Click here to install Java now)

This event is a part of the ongoing Math 2.0 interest group conversation series. Always-discussed topics:
• principles of Math 2.0 teaching and learning
• networks and communities creating social math objects
• platforms for remote communication of this interest group
• our projects and collaboration
• publishing efforts and bibliography