Desmos, which is available at desmos.com, is a very powerful free graphing calculator app that is available across most devices, including Chromebooks, desktop and laptop computers, and mobile devices/tablets. Most secondary math teachers have at least heard of Desmos, but many are not aware of the library of student activities available at teacher.desmos.com. Middle and elementary math teachers also tend to be unaware of this, as Desmos is a graphing app and graphing functions is usually not taught prior to eighth grade. Nevertheless, there are several activities that are available at this site that are appropriate for students in lower grades.
Polygraph is a game, similar to “Guess Who”, where a “picker” selects one out of sixteen objects (graphs or shapes) and another student, the “guesser”, asks yes/no questions to narrow down which of the sixteen objects his or her partner chose. All you have to do is select the activity, generate a code, and Desmos does all of the work of pairing up students (randomly) and then they start playing! I had a group of younger students at Math Monday last night, so I had them play Polygraph: Shaded Rectangles. As you can see below, the students asked questions that required both the picker and the guesser to think deeply about fractions and their visual representations. There are other Polygraphs where students are presented with fractions in number form. Although most of the Polygraph activities are focused on graphing functions, there are a few that involve basic fractions and polygons that can be used with younger students.
Another favorite Desmos game for my younger kids is Tile Pile. In this activity, students begin by tiling a 4 square foot section of floor. Then they use estimations and a t-chart/table to predict the number of tiles that would be needed to cover larger floor sizes. By creating a ratio table, students are building a table of values that could be graphed to form a linear function. Although the activity is listed as appropriate for sixth graders, I was able to engage third and fourth graders with this fun activity.
All in all, don’t dismiss Desmos as just an app for graphing. There are many dynamic activities available at teacher.desmos.com for all math teachers, including elementary and middle school educators.