LEGO Stoichiometry Activity

Stoichiometry often proves to be a challenging topic for high school chemistry students, primarily due to its abstract nature and the reliance on rote memorization for problem-solving techniques rather than a conceptual understanding. Recognizing this common struggle, I sought to design an activity that would not only reinforce the fundamentals of stoichiometry but also deepen students' grasp of the particulate nature of matter, laying a stronger conceptual foundation for later problem-solving.¹

After searching for resources, I stumbled upon Eric Witzel’s "LEGO Stoichiometry" activity published in the Journal of Chemical Education.² While the concept was intriguing, I thought that it might be too advanced for my students, and it required specialized LEGO³ building kits that weren't readily available. Inspired by Witzel's approach, I decided to develop my own LEGO stoichiometry activity, geared for my students and designed in a format reminiscent of Process Oriented Guided Inquiry Learning (POGIL).⁴

In my version of the activity, students are first tasked with constructing unique designs using a standardized set of LEGO pieces (image 1). By ensuring each student group receives identical sets of LEGO pieces, we would all have the same calculations, making it easier to discuss and collaborate. 

I used this activity at the beginning of my stoichiometry unit, and the completion of the activity fit well within my 85-minute class period. Students really enjoyed creating their own designs, naming them, and comparing them with other groups. We often referred back to the activity later in the unit, and it seemed to provide a good anchor for students to refer back to when struggling with more complicated stoichiometry problems. 

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Image 1: Different student designs.

Tips and Tricks

1. I utilized four different colored LEGO pieces, varying the quantity of each to simulate the reactants in a chemical reaction. Each student group received a total of eight LEGO pieces: four 1x1 yellow pieces, two 3x2 blue pieces, one 6x1 red piece, and one 4x2 green piece.
2. Due to a shortage of additional LEGO pieces, I opted to create a PDF featuring images of the pieces to provide students with different sample configurations (image 2). While the pictures served their purpose, I wish I had enough extra pieces for a more hands-on approach that would allow students to physically construct products and experience the concepts of limiting and excess reactants firsthand. Ideally, having an ample supply of extra LEGO pieces and creating physical samples would enhance the tactile experience for students.

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Image 2: Printout showing pictures of different LEGO samples.

References

1. Kimberlin, S., & Yezierski, E. (2016). Effectiveness of inquiry-based lessons using particulate level models to develop high school students’ understanding of conceptual stoichiometry. Journal of Chemical Education, 93(6), 1002-1009.
2. Witzel, J. E. (2002). Lego stoichiometry. Journal of Chemical Education, 79(3), 352A. https://pubs.acs.org/doi/epdf/10.1021/ed079p352 
3. www.lego.com 
4. https://pogil.org/