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Topics: Arithmetic, algebra
Material: Pencil and Paper
Grades: 4, 5, 6, 7, 8, 9
Common Core: 4.OA.1, 4.OA.2, 4.OA.3, 4.OA.5, 5.OA.3, 6.EE.2, 6.EE.3, 6.EE.4, 7.EE.
3, 8.NS.1, A-CED.1, A-CED.2, MP1, MP2, MP3, MP5, MP6, MP7, MP8
This trick is an extraordinary introduction to the power of algebraic thinking, and a reminder of what makes algebra so awe-inspiring
This trick is an extraordinary introduction to the power of algebraic thinking, and a reminder of what makes algebra so awe-inspiring.
A video Launch for this lesson is available in two parts. PDF of the lesson is below the videos.
New! Video Overview
Slides mentioned in the video are here: Math Magic Trick Slides
Use just the first two slides to introduce the trick. The later slides provide an explanation/hint of how it works.
Alternate Video and Class Launch Part 1
Part 1. When using as a class launch, stop at 2:45 and let the class come up try to find their own counterexamples.
Video Part 2: Solution
Part 2 – the solution to the magic trick.
What we love about the Math Magic Trick
This deceptively simple trick can differentiate broadly. Some students can use it to practice arithmetic or get practice with the rules for, say subtracting negative numbers or dividing fractions, or even whole numbers.
It can also be used to highlight the full power of the algebraic toolset. This one is a favorite.