Learning Goal: Understand the purpose and meaning of the point of intersection and make connections between representations.
3 Act Math
- Stacking Cups (Andrew Stadel)
- Use big whiteboards and have each group member write with different colors
- Write pre-scripted questions for audience members to ask during presentations
Classwork
- Connection Handout
- Go over Concept Quiz
- Students complete analysis handout in order to prepare for retake. See retake policy and learning folders post for more details.
Answers
Standards
- Common Core
- HSA.REI.C.6 – Solve systems of linear equations exactly and approximately (e.g., with graphs), focusing on pairs of linear equations in two variables.
- TEKS
- A.5(C) – solve systems of two linear equations with two variables for mathematical and real-world problems
When Math Happens 
I used this as a introduction to systems and really liked it. I especially loved that students noticed the “equal” stacks weren’t exactly equal. How did you explain the y-intercept for zero cups wasn’t zero centimeters in a way that made sense to students?
Thank you for the comment and feedback! Andrew Stadel did a great job designing that lesson.
For the y-intercept, I told them that it would make more sense to label our table as the number of cup rims for the x values and the total height for the y values. That way, if you take away all the rims, theoretically there would still be the base of the cup left over. Also, I really tried to emphasize how the height was changing. It was growing by an additional cup rim each time. Then, I asked what stayed the same the whole time which was the base of the cup.
Let me know if that helps!