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Technology Review Section Editor: Christophe Hirel

In this section, we feature websites, online manipulatives, and web-based applications that are appropriate for K-12 mathematics instruction. We are looking for critical reviews of technologies which focus on both the benefits and limitations of using these tools in a K-12 mathematics classroom. If you use a technological tool and wish to share with us, please respond to the call for manuscripts on page 51.

Christophe Hirel Section Editor,

Technology Review chirel69@yahoo.com

Graphing with Desmos Abby Smith

Desmos is a free online graphing website accessible to students and teachers on their com- puters, tablets, and phones. The website is designed to allow students to interact with graphical repre- sentations of equations and tables. Not only does the website allow students to examine graphs, but there are also pre-designed class activities that teachers can freely use in their classroom. When www.desmos.com/calculator is open- ed, students are led to a page where they can type in two-variable equations and a graph appears of the equation. Multiple equations can be graphed at the same time. Students can even remove the visu- als of a specific equation without deleting it by clicking the circle to the left of the equation. In addition to equations, students can type in func- tions, inequalities, and tables of values. The main drawback is that students are restricted to two vari- ables. In order to help students examine how graphs change based on the variables included in the equation, sliders (which change the value of a specific variable) are also available for students to manipulate their equations. While it is not neces- sary to set up an account with Desmos, if students log in, they can save their work to return to it at a later date. As a middle and high school math teacher, I always have enjoyed the lessons where we break out the tablets or visit the computer lab to spend a day exploring specific graphs of functions, discuss- ing the constraints on the graph, or wondering how transformations change the way the graph ap-

pears. The website lends itself well to inquiry- based learning, meaningful mathematical conversa- tions, and a way for struggling students to connect to the content; however, there are downsides to using the software as well. The Desmos software is user-friendly for students and teachers. Many of the students I have worked with download the Desmos app to their phones after I show them how to use the site. As a teacher, I understand that this is a blessing and a curse. On the bright side, students can use the gra- phing tools to make their own conclusions on how specific equations are graphed and why the graphs take on the specific shapes. Sadly, not all students Figure 1. An example of how to use Desmos to help students explore quadratic functions and the transformations that oc- cur to the graph given different values of a, b, and c.

Virginia Mathematics Teacher vol. 44, no. 1

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