Exploding Dots

5.1 Welcome

Lesson materials located below the video overview.

Addition, subtraction, multiplication. Now it is time for division.


Here’s an example of a division problem:  Compute \(276 \div 12\).


And here’s a horrible way to solve it:  Draw a picture of \(276\) dots on a page and then circle groups of twelve dots. You will see, after about an hour, that there are \(23\) groups of twelve in a picture of \(276\).


Here’s a great way to solve it: Draw a picture of \(276\) dots in a \(1 \leftarrow 10\) machine and just see right away that there are \(23\) groups of twelve in it! 


Read and play on to see how we can do this.


Cool Fact: Did you that the division symbol \(\div\) is called an obelus?


Supplementary Content for this Experience:

PDF files of this first chapter

Chapter 5 EXPLODING DOTS (English)

Chapter 5 EXPLODING DOTS Bulgarian (Translated by Stanislav Chobanov)

Chapter 5 EXPLODING DOTS Chinese (Translated by Xinli Wang)

Chapter 5 EXPLODING DOTS Spanish (Translated by Cindy Weitzman)


A PDF guide for teaching this experience

Scolab‘s fully interactive web experience

Additional apps by Geogebra, Wolfram, Chee Wei Tan, Ken Wessen, Ulrich Kortenkamp, and more!

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Guides & Solutions

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