Infinity: An Alternate Elective After Algebra 2 Henri Picciotto - - PowerPoint PPT Presentation

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Infinity: An Alternate Elective After Algebra 2 Henri Picciotto - - PowerPoint PPT Presentation

Infinity: An Alternate Elective After Algebra 2 Henri Picciotto The Urban School of San Francisco henri@MathEducationPage.org www.MathEducationPage.org Infinity: An Alternate Elective After Algebra 2 Henri Picciotto The Urban


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Infinity: An Alternate Elective After Algebra 2

Henri Picciotto

The Urban School of San Francisco henri@MathEducationPage.org www.MathEducationPage.org

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Infinity: An Alternate Elective After Algebra 2

Henri Picciotto

The Urban School of San Francisco math-ed@picciotto.org www.picciotto.org/math-ed

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Math Courses

not tracked / grade levels & acceleration

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Infinity overview

Who takes the class Four topics Readings Algebra review Computer tools Juniors, before Calculus Seniors, instead of

  • r in addition to

Calculus

not all superstars

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Infinity overview

Who takes the class Four topics Readings Algebra review Computer tools Infinite sets Proof Chaos Fractals

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Infinity overview

Who takes the class Four topics Readings Algebra review Computer tools Galileo, Jorge Luis Borges, Douglas Hofstadter, Martin Gardner, Lewis Carroll, James Gleick, Scientific American, ...

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Infinity overview

Who takes the class Four topics Readings Algebra review Computer tools prime numbers, algebraic fractions, similarity, proportions, sequences and series, iteration, logarithms, complex numbers, ...

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Infinity overview

Who takes the class Four topics Readings Algebra review Computer tools Fathom Boxer

Boxer is a key part of the course, but I won’t show that part.

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Galileo

1564-1642

Infinite sets Proof Chaos Fractals

Get two people to read the dialogue

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Infinite sets Proof Chaos Fractals

Georg Cantor 1845-1918

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Equivalence

Two sets are equivalent if their elements can be put in a one-to-one

  • correspondence. Example:

{1, 2, 3} {a, b, c}

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{0, 1, 2, 3, …} {1, 2, 3, 4, …}

Equivalence

Two sets are equivalent if their elements can be put in a one-to-one

  • correspondence. Example:
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[5, 7] and [12, 19]

Equivalence

Two sets are equivalent if their elements can be put in a one-to-one

  • correspondence. Example:

5 7 12 17

Cabri file: intervals

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[0,∞) and (0,∞)

Equivalence

Two sets are equivalent if their elements can be put in a one-to-one

  • correspondence. Example:

f(x) = x + 1 if x is a natural number x

  • therwise

⎧ ⎨ ⎩

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Thinking about Infinity

Infinite sets Proof Chaos Fractals

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Proof by contradiction

Prime Numbers

Infinite sets Proof Chaos Fractals

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the integers {0, 1, -1, 2, -2, 3, -3, ...}

Countable Infinite Sets

An infinite set is said to be countable if it is equivalent to the natural numbers. Example:

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the rationals

Countable Infinite Sets

An infinite set is said to be countable if it is equivalent to the natural numbers. Example: 2 −2 2 −1 2 1 2 2 1 −2 1 −1 1 1 1 2 −2 −1 1 2 −1 −2 −1 −1 −1 1 −1 2 −2 −2 −2 −1 −2 1 −2 2

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"The Power of the Continuum"

The set of real numbers in the interval [0, 1] is not countable

proof by contradiction [0, 1] is equivalent to whole real line, and even to the whole plane

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The Devil's Challenge

Raymond Smullyan

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The Strong Law of Small Numbers

Infinite sets Proof Chaos Fractals

#5. 40 / #6. 127 / #7. 432 / #8. 5777 / #9. not known

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Infinite sets Proof Chaos Fractals Will this pattern break down? It seems like a power of 4 minus 1 is always a multiple of 3

conjecture supplied by me

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Generating conjectures

conjecture hinted at by me

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Fibonacci conjectures

  • start with student-generated conjectures, then make suggestions
  • proofs by mathematical induction, algebraic manipulation, a method

involving dominoes, and...

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An explicit formula for Fibonacci numbers?

breaks down at 11 Actual formula: see work sheet on my Web site

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Infinite sets Proof Chaos Fractals

Iterating Functions

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Iterating Linear Functions

  • In Algebra 2, an engaging introduction to

sequences, series, and limits

  • In this class, a prelude to the study of

iterating non-linear functions, dynamical systems, and chaos

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Infinite sets Proof Chaos Fractals

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Infinite sets Proof Chaos Fractals

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Infinite sets Proof Chaos Fractals

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Infinite sets Proof Chaos Fractals

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Infinite sets Proof Chaos Fractals