history of mathematic

We are now doing history of mathematic using

The Secret Life of Math.

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I bought this book from Book Depository because it's cheaper

compared to other online bookstores

(free shipping worldwide).

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There are at least one hands-on every chapter.

Here is a Native American-styled "animal skin" tally marks.

(we didn't do the chicken bone tally stick, our cat ate the bone!!)

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This is an Inca Quipu.

(count and add-on with knots)

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While reading this book to XP,

she drew this picture.