When I was a child (back in the 1980s), my friends and I loved playing a guessing game called Guess Who? In this game, one person chose a character and the other person had to ask yes or no questions to determine which character was chosen. Desmos has created a math version of this, Polygraph.
I often use Polygraph with my students at the beginning of a unit, when I am introducing a topic. Shown below is the Polygraph I used with my 7th-grade accelerated group at the beginning of our Transformations unit. Students are shown an array of choices. One student picks a choice that the other students must ask yes or no questions to identify. The goal is that students are able to guess the correct choice with the least amount of questions.
My class has not reviewed or discussed the vocabulary for this unit, yet. They have had previous experiences with the coordinate plane. This activity allows me to see who remembers vocabulary from prior units and who may need a bit of a review. It also gives my students a need to know the vocabulary so that they can “win” the game. As shown below, many of my students learn to be precise (MP6) in their questions. While the students below may not remember the proper vocabulary (quadrants,) they are able to clearly describe their question.
Running a Polygraph in Class
I often use Polygraphs as a warmup in my classroom. I place the activity code on my whiteboard and have students sign in using their Google login (this allows them to log in at a later date if need be.) All of the Polygraph activities start with a practice round that resembles the board game in that students choose a person for another student to guess. Students have the option of skipping this round.
After the practice round, students are randomly assigned a partner by the program. One of the pair is asked to choose a picture that their partner must guess. I find that many of my students try to choose the picture that they think is the trickiest to guess. Once the “picker” makes their choice, the “guesser” is prompted to ask a yes or no question. Once the question is asked, the “picker” answers yes or no. The “guesser” then eliminates all graphs that fulfill the answer they have received. I have the students play for a couple of rounds (about 10-15 minutes) then I pause and anonymize the activity. The class is then prompted “What did you notice? What do you wonder?” and we discuss what questions they have on the diagrams. I also may project some of the conversations.
The two students below had some interesting questions. What question might someone ask so that the “guesser” could have won more easily?
The “guesser” below guessed incorrectly. What might you have asked in order to “win” the game? What words might they have used to better clarify their questions?
After our discussion, my students start their lesson on that day’s topic. Many students beg me to unpause the Polygraph so that they can “play” in the evening with their classmates for “fun” - I’m happy to oblige. I often replay this game with students at the end of the unit and see a great increase in understanding of the appropriate language and mathematical vocabulary in my students.