The trouble with 5 examples socal nev section maa meeting october 8 2005
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The Trouble with 5 Examples SoCal-Nev Section MAA Meeting October 8, 2005. Jacqueline Dewar Loyola Marymount University. Presentation Outline. A Freshman Workshop Course Four Problems/Five Examples Year-long Investigation Students’ understanding of proof.

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The trouble with 5 examples socal nev section maa meeting october 8 2005

The Trouble with 5 ExamplesSoCal-Nev Section MAA MeetingOctober 8, 2005

Jacqueline Dewar Loyola Marymount University


Presentation outline

Presentation Outline

  • A Freshman Workshop Course

  • Four Problems/Five Examples

  • Year-long Investigation

    • Students’ understanding of proof


The math 190 191 freshman workshop courses

The MATH 190-191 Freshman Workshop Courses

  • Skills and attitudes for success

  • Reduce the dropout rate

  • Focus on

    • Problem solving

    • Mathematical discourse

    • Study skills, careers, mathematical discoveries

  • Create a community of scholars


Regions in a circle what does this suggest

Regions in a CircleWhat does this suggest?


Prime generating quadratic

Prime Generating Quadratic

Is it true that for every natural number n,

is prime?


Count the zeros at the end of 1 000 000

Count the zeros at the end of 1,000,000!


The trouble with 5 examples socal nev section maa meeting october 8 2005

Observed pattern:

If 4 divides n, then n! ends in zeros.

Counterexample:

24! ends in 4 not 5 zeros.


Where do the zeros come from

Where do the zeros come from?

From the factors of 10,

so count the factors of 5.

There are

Well almost…


Fermat numbers

Fermat Numbers

  • Fermat conjectures (1650) Fn

    is prime for every nonnegative integer.

  • Euler (1732) shows F5 is composite.

  • Eisenstein (1844) proposes infinitely many Fermat primes.

  • Today’s conjecture: No more Fermat primes.

=


The trouble with 5 examples

The Trouble with 5 Examples

Nonstandard problems give students more opportunities to show just how often 5 examples convinces them.


Year long investigation

Year-long Investigation

  • What is the progression of students’ understanding of proof?

  • What in our curriculum moves them forward?


Evidence gathered first

Evidence gathered first

  • Survey of majors and faculty


Respond from strongly disagree to strongly agree

Respond from Strongly disagree to Strongly agree:

If I see 5 examples where a formula holds, then I am convinced that formula is true.


5 examples students faculty

5 Examples: Students & Faculty


Faculty explanation

Faculty explanation

‘Convinced’ does not mean ‘I am certain’…

…whenever I am testing a conjecture, if it works for about 5 cases, then I try to prove that it’s true


More evidence gathered

More evidence gathered

  • Survey of majors and faculty

  • “Think-aloud” on proof - 12 majors

  • Same “Proof-aloud” with faculty expert

  • Focus group with 5 of the 12 majors

  • Interviews with MATH 191 students


Proof aloud protocol asked students to

Proof-Aloud Protocol Asked Students to:

  • Investigate a statement (is it true or false?)

  • State how confident, what would increase it

  • Generate and write down a proof

  • Evaluate 4 sample proofs

  • Respond - will they apply the proven result?

  • Respond - is a counterexample possible?

  • State what course/experience you relied on


The trouble with 5 examples socal nev section maa meeting october 8 2005

Please examine the statements:

For any two consecutive positive integers, the difference of their squares:

(a) is an odd number, and

(b) equals the sum of the two consecutive positive integers.

What can you tell me about these statements?


Proof aloud task and rubric

Proof-aloud Task and Rubric

  • Elementary number theory statement

    • Recio & Godino (2001): to prove

    • Dewar & Bennett (2004): to investigate, then prove

  • Assessed with Recio & Godino’s 1 to 5 rubric

    • Relying on examples

    • Appealing to definitions and principles

      • Produce a partially or substantially correct proof

  • Rubric proved inadequate


R g s proof categories

R&G’s Proof Categories


Students level relative critical courses

Students’ Level Relative Critical Courses


Level in major vs proof category

Level in Major vs Proof Category


Multi faceted student work

Multi-faceted Student Work

  • Insightful question about the statement

  • Advanced mathematical thinking, but undeveloped proof writing skills

  • Poor strategic choice of (advanced) proof method

  • Confidence & interest influence performance


Proof aloud results

Proof-aloud results

  • Compelling illustrations

    • Types of knowledge

    • Strategic processing

    • Influence of motivation and confidence

  • Greater knowledge can result in poorer performance

  • Both expert & novice behavior on same task


How do we describe all of this

How do we describe all of this?

  • Typology of Scientific Knowledge (R. Shavelson, 2003)

  • Expertise Theory (P. Alexander, 2003)


Typology mathematical knowledge

Typology: Mathematical Knowledge

  • Six Cognitive Dimensions (Shavelson, Bennett and Dewar):

    • Factual: Basic facts

    • Procedural: Methods

    • Schematic: Connecting facts, procedures, methods, reasons

    • Strategic: Heuristics used to make choices

    • Epistemic: How is truth determined? Proof

    • Social: How truth/knowledge is communicated

  • Two Affective Dimensions (Alexander, Bennett and Dewar):

    • Interest: What motivates learning

    • Confidence: Dealing with not knowing


School based expertise theory journey from novice to expert

School-based Expertise Theory: Journey from Novice to Expert

3 Stages of expertise development

  • Acclimation or Orienting stage

  • Competence

  • Proficiency/Expertise


Mathematical k nowledge e xpertise g rid

MathematicalKnowledge Expertise Grid


Mathematical k nowledge e xpertise g rid1

MathematicalKnowledge Expertise Grid


Implications for teaching learning

Implications for teaching/learning

  • Students are not yet experts by graduation

    e.g., they lack the confidence shown by experts

  • Interrelation of components means an increase in one can result in a poorer performance

  • Interest & confidence play critical roles

  • Acclimating students have special needs


What we learned about math 190 191

What we learned aboutMATH 190/191

  • Cited more often in proof alouds

    • By students farthest along

  • Partial solutions to homework problems

    • Promote mathematical discussion

    • Shared responsibility for problem solving

    • Build community


The trouble with 5 examples socal nev section maa meeting october 8 2005

With thanks to Carnegie co-investigator,

Curt Bennett

and Workshop course co-developers,

Suzanne Larson and Thomas Zachariah.

The resources cited in the talk and the Knowledge Expertise Grid can be found at

http://myweb.lmu.edu/jdewar/presentations.asp


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