In the last couple years I was introduced to GeoGebra – I am not exactly sure where I first heard of it – and I found that I really liked it. It’s interface seemed more conducive, to me at any rate, to integrating Algebra and Geometry. The drop down menus with their pictures were very nice and the box on the left keeping track of what objects had been created was great. I still primarily used Sketchpad because it was what I was familiar with.
The biggest argument in favor of continued use of Geometer’s Sketchpad is the sheer wealth of material out there for many different subjects and topics that specifically reference GS. The biggest argument in favor of GeoGebra is its cost. It is free. While I think that, all things being equal, GeoGebra is a slightly nicer program to use that in itself is not sufficient to choose it over the standard GS. But the price, in my mind, is the tipping point. I can write my own materials that make use of GeoGebra, but nothing I can do will lower the price of GS for my students. Having this tool in their hands is an essential part of learning geometry in my class.
Of course I should also mention that more and more people are writing things for GeoGebra, particularly files that can be used. Check here, here, here, or here.
I expect my students to explore, make discoveries, make conjectures, and write proofs. Three of those four can be aided by a piece of dynamic geometry software. GeoGeobra is my choice.
Here are a couple screenshots:
This is what you first see when you open the program. The axes can be turned on or off and, in fact, you can set the default so that it opens without the axes.
Notice the bar at the bottom. This is where you can type in equations to graph.
This is the primary toolbar. As you can see, each button gives you a picture of a particular construction or object. When you click open the menu the same is true for all the choices, plus a text description.
This menu is very nice, and much easier for kids to follow I believe. Remembering to click the little down arrows when I want to see the whole menu is about the hardest part. Drawing objects is easy as well:
Note the list at the left of created objects. Very easy to create objects.
And finally, as you can see from below, it is easy to graph functions and then attach geometric objects to them.
You can also create scripts to do various automated tasks as well.
This year I will be using this exclusively with my students and comparing it with how well previous groups did with Sketchpad.
Update (9/8/08): I am in the midst of rewriting Sketchpad activities, and I just came across something that could be a deal breaker for some in switching from Sketchpad to GeoGebra. GS has a very easy interface for creating animations. GeoGebra apparently needs some knowledge of writing scripts, which will make it prohibitive to having 9th grade Geometry students do them. For now I am going to develop some workarounds – mainly bypassing the animations I used to do with GS – and see how that works. Once I am done adapting a few more of the investigations I will do a full post on how things went.
