## 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)

COMING SOON:

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!

## Books

Take your understanding to the next level with easy to understand books by James Tanton.

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## Guides & Solutions

Dive deeper into key topics through detailed, easy to follow guides and solution sets.

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