CS382:Unit-foundation

Fermiproblems - Use fermiproblems to encourage students to be comfortable making estimates and discovering ways to estimate with only limited data available. Worked examples are available here

• A list of Problems is available here

Scheduling

Needs to be first

Preferably followed by static modeling

Skill-set

• Using available sources to find information
• Quickly vetting sources
• Acquiring a feel for how to determine what factors are significant
• Learning how to make estimates where figures are not available
• Learning how to show and defend the reasoning behind extrapolations
• Being able to make quick back of the napkin calculations
• Understanding of what significant figures are and how to calculate them
• Understanding the difference between accuracy and precision

Materials needed

• Problems which are relevant to the models which the students will later be constructing in the class
• Worked through examples showing a complete model and demonstrating which information is necessary for a ballpark estimation and which is not.
• Problem sets for the students to work through
• A quick example of scale such as powers of 10

Lecture Outline

Lectures are ideally divided into 3, What data to get, Where to get the data, and What to do with the data. However since the 3rd part is shorter than the other two it is feasible to divide into two lectures after discussing that making all your own data is hard. How to build a model

• What data do you get?
  • Establishing a feeling for what is significant
    • Bring in a jar of Jelly beans. Ask students to guess how many there are. Ask for which measurements are necessary to get a good guess.
    • Ask a big question... IE what is the area of the Heart. Brainstorm. (This provides a theoretical background to the measuring lab.
  • Establish a feeling for what is too detailed
    • Explain what the difference is between a back of the napkin calculation and an exhaustive one
    • Provide an example of a model and how to make it tractable.
      • Dropping a ball 10 meters (useful data: Gravity not really useful: Drag, Gravity at our altitude ball surface etc.)
  • Introduce the idea of orders of magnitude
    • Talk about fermi-problems
• Where do you get data?
  • Making all your own data is hard.
    • Unlike in high-school copying is good, just remember to cite
    • We don't want to reinvent the wheel each time we build something.
    • Ask how many piano tuners there are in Chicago
      • Work through the fermiproblem
  • But do we trust other people's data?
    • Discuss the notion of vetting sources
    • explain scientific rigor
• What do you do with your data?
  • We need to extrapolate sometimes
    • Explain how to properly extrapolate from known data to what you need.
    • Explain how to defend your extrapolations (Show calculations, explicitly list assumptions, etc)
  • Show how to bring data together
    • Revisit the worked fermi-problem
  • Explain that data can be evaluated based on accuracy and precision. Explain the difference between them

Lab Work

• Take a lab period to rework a wikipedia article.
  • this couples learning wiki syntax and vetting information
  • Split up into groups of 2-3.
  • Give each group a page which we have identified as needing work and being at least incidentally relevant to the course.
  • Provide a tutorial of how to edit wiki's
  • Make sure that members of the group switch out who does the editing and who does the research.

Background Reading

Edward Tufte, Sparklines Theory and Practice

Shiflet Chapter 1

how to edit mediawiki.

Classroom Response

Which of the following represents low accuracy but high precision:

A) 5 measurements of a meter stick which measure the length as 100cm, 101cm, 99cm, 98cm, 100cm.

B) 5 measurements of a meter stick which measure the length as 80cm, 79cm, 81cm, 82cm, 78cm.

C) 5 measurements of a meter stick which measure the length as 90cm, 110cm, 109cm, 91cm, 100cm

D) 5 measurements of a meter stick which measure the length as 80cm, 95cm, 50cm, 130cm, 200cm.

Which of the following is likely to have the least impact on a model of a ball dropping:

A) Rate of acceleration due to gravity

B) Size of the ball

C) Height of the ball

D) Whether or not the ball is attached to a parachute

Which of the following websites best represents a reliable source for scientific research?

A) facebook.com

B) Wikipedia.com

C) acm.org

D) ebay.com

Comments

Pros

• What makes a good model vs. what makes just a model

Cons

Comments

• Is this included in all of the other units, or also use this and then use these skills in lots of other places?
  • We need to make sure that this - if it's a unit on its own - that it isn't a very boring first unit
• Include talking about orders of magnitude, scale, significant figures, accuracy vs. precision, pattern recognition

To Do

• Sam has a high school teacher who has a list of many examples, he is going to get in contact with them.
• Think about and perhaps talk to Fitz/Brad about how much from Fire could be used to address this foundation unit