UNO OUT…..Demystifying Stoichiometry

I enjoy playing UNO, a popular card game by Mattel, with my family. Students enjoy playing UNO with their friends during lunch or at the end of the day at my school. As a teacher, I have also experienced students having difficulty using dimensional analysis to solve stoichiometry problems. Students have issues with setting up and solving stoichiometry problems. In the past, I’ve used examples from the English system of measurement to remind students that they have been using dimensional analysis, one of the skills needed to solve stoichiometry problems since elementary school when they converted inches to feet. This article will explain how I merged students and my enjoyment of playing UNO to build student confidence to set up and solve stoichiometry problems.

In chemistry, stoichiometry is a new language for students to understand the Next Generation Science Standards (NGSS) HS-PS1-7: Use mathematical representations to support the claim that atoms, and therefore mass, are conserved during a chemical reaction (NGSS Lead States, 2013). To demonstrate proficiency in NGSS HS-PS1-7, students must grasp the Science & Engineering Practice of Using Mathematics and Computational Thinking, the Disciplinary Core Idea of Chemical Reactions, and the Crosscutting Concepts of Energy and Matter (National Research Council, 2012). 

First, students need to know the concept of moles since they aren’t talking about moles in their everyday lives. It’s a challenge for students to accept the idea of the mole and then use it to set up and solve stoichiometry problems. To introduce the mole, I use counting words like the pair (2), dozen (12), and ream (500) as ways to get students to realize the mole in chemistry refers to a specific number, Avogadro constant (6.022140857 x 10²³ mol^-1) to quantify atoms, molecules, ions, and formula units (Libre Texts). Next, I tap into students’ prior knowledge of the International System of Units (SI) by having students walk through some time conversions, such as converting hours to days, and tell them the mole is also a unit of measurement for the amount of a substance in the SI system. Then, I tell students that dimensional analysis is a problem-solving method that converts one unit of measurement to another unit of measurement using conversion factors. These conversion factors are fixed and unchanging relationships.

In the next class, students walk in, and I tell them to play UNO. They are initially shocked and hesitant but start to play and even teach other students how to play, so I give them time to get comfortable playing UNO. I asked students to explain how to play it, such as what happens with the UNO reverse and wild cards. Then, I show students the UNO conversions, aka mole conversions cards. We discuss that the molar mass conversion factor is 1 mol (same substance) = grams (molar mass) (same substance), which the blue UNO reverse card will represent. We also discussed that students can reverse the molar mass conversion factor. 1 mole can be on top (numerator) and molar mass on the bottom (denominator), but it must be the same substance. Avogadro conversion factors are on the green UNO reverse card, and Volume at STP 22.4 L = 1 mole is on the yellow UNO reverse card. The UNO wild card works well as the mole-to-mole conversion factor because, in UNO, you can use it to change to different colors, so students can use it to convert to other substances for mole conversions. It also explicitly reminds students that the moles come from the coefficients in the balanced chemical equation. 

Then, we use the GUESS problem-solving method to solve stoichiometry problems. Students identify the given, unknown equation (balanced) and set up to solve stoichiometry problems. I inserted the UNO conversion factor cards into the set-up section of the G.U.E.S.S. method. 

Connecting dimensional analysis to the UNO card game my students and I enjoy has made teaching stoichiometry more enjoyable and accessible for them. 

I would like to acknowledge the help of Dr. Mindy Chappell of Portland State University in completing this work.

References

1. National Research Council. A Framework for K−12 Science Education: Practices, Crosscutting Concepts, and Core Ideas; National Academies Press: Washington, DC, 2012.
2. NGSS Lead States. Next Generation Science Standards: For States, by States; National Academies Press: Washington, DC, 2013.
3. Libretexts. (2023, January 30). The Mole and Avogadro’s constant. Chemistry LibreTexts.https://chem.libretexts.org/Bookshelves/Physical_and_Theoretical_Chemistry_Textbook_Maps/Supplemental_Modules_
   (Physical_and_Theoretical_Chemistry)/Atomic_Theory/The_Mole_and_Avogadro's_Constant