Thursday, July 18, 2013
From The College Board: Reconciling AP Exams With Common Core
Sunday, June 1, 2008
Academic (Math) Slums
Economist Walter Williams weighs in on the academic atrocity also known as 'fuzzy math':
American education will never be improved until we address one of the problems seen as too delicate to discuss. That problem is the overall quality of people teaching our children. Students who have chosen education as their major have the lowest SAT scores of any other major. Students who have graduated with an education degree earn lower scores than any other major on graduate school admissions tests such as the GRE, MCAT or LSAT. Schools of education, either graduate or undergraduate, represent the academic slums of most any university. As such, they are home to the least able students and professors with the lowest academic respect. Were we serious about efforts to improve public education, one of the first things we would do is eliminate schools of education.
The inability to think critically makes educationists fall easy easy prey to harebrained schemes, and what's worse, they don't have the intelligence to recognize that the harebrained scheme isn't working. Just one of many examples is the use of fuzzy math teaching techniques found in "Rethinking Mathematics: Teaching Social Justice by the Numbers." Among its topics: "Sweatshop Accounting," "Chicanos Have Math in Their Blood," "Multicultural Math," and "Home Buying While Brown or Black." The latter contains discussions on racial profiling, the war in Iraq, corporate control of the media, and environmental racism.
If you have a fifth-grader, his textbook might be "Everyday Math." Among its study questions are: If math were a color, it would be —, (blank) because —. (blank). If it were a food, it would be —, (blank) because —. (blank). If it were weather, it would be —, (blank) because —. (blank). All of this is sheer nonsense, and what's worse is that the National Council of Teachers of Mathematics sponsors and supports much of this nonsense.
Mathematics, more than any other subject, is culturally neutral. The square root of 16 is 4 whether you're an Asian, European, or African, or even a Plutonian or Martian. While math and science literacy among white 15-year-olds is nothing to write home about, that among black 15-year-olds is nothing less than a disaster.
Few people appreciate the implications of poor math preparation. Mathematics, more than anything else, teaches one how to think logically. As such, it is an important intellectual tool. If one graduates from high school with little or no preparation in algebra, geometry and a bit of trigonometry, he is likely to find whole areas of academic study, as well as the highest paying jobs, hermetically sealed off from him for his entire life.
You can read the entire article here. For those interested, Williams has a number of syndicated columns over the past few years that are quite critical of the declining 'educational' departments in American universities.
Thursday, July 19, 2007
Problem complexity and higher-order thinking
Monday, April 30, 2007
Sunday, February 11, 2007
why formalism is important
Let's look at this whole thing cognitively and take as our first couple of examples what most would consider to be relatively simple statistics problems:
- Lessen Waist, Inc. produces low-fat cereals, which they sell in 12-ounce (weight) boxes. Because of settling and production scheduling, Lessen Waist cannot weigh every box of cereal, and 0.35 ounces (weight) is considered to be an acceptable variance from the advertized weight. Lessen Waist weighs a subset of boxes because the filling machines must be adjusted periodically. Use the sample weights below and the appropriate statistical tests to determine if the boxes of cereal are within the acceptable weight. If they are not, use the appropriate statistical tests to determine how much the filling machines need to be adjusted.
- Jennie's Rugs has been aggressively marketing their products on the web with Google ads and popups over the last twelve months. Below are the ad costs for both types of ads and the sales revenue for the last twelve months, as well as the sales revenue (before Jennie's Rugs started advertising on the web) for the previous twelve months. First, use the appropriate statistical tests to determine if the web ads have had any statistically significant effect on the sales renenues. If so, use the appropriate statistical test to determine if the sales revenues for the second twelve months can be predicted from either of the web ad types. Report all relevant statistics, and if relevant, include the formula to predict the sales revenue from the web advertising.
The first problem students have -- because a problem is more complex than most realize -- is parsing the text of the problem. Far too many students experience some kind of frustration just reading the problem, and find it even more frustrating to try to get past the first reading (sorry to be cliché, but if I had a dollar for every time a student has come to office hours and expressed exasperation at being required to figure out how to figure out the "story problem," I'd have my own island in the Caribbean). And this problem is getting worse.
Let's return to formalism. Students -- again, judging from what those who come see me say and (don't) do -- shut down when math is involved (yes, even in a statistics class -- as if they expected it to be, well, I'm not sure what, though I've often wondered), and from what I've observed, much of the reason is because they see math as some kind of abstruse knowledge expressed in some kind of foreign language. Students ten years ago were much more likely to understand something when you wrote equations on the board than now, when more and more students give you the deer in the headlights.
I think that's partly because it is a foreign language due to lack of exposure, and a de-emphasis of formalism.
But once they get past the first reading of the problem, they have to do a number of things: Decide how best to solve the problem, extract any essential information, determine what additional calculations they may need to do, then set up the problem and solve it. So yes, if you're statistically literate, either of the problems seems almost childishly simple, but to an undergrad, both are actually pretty complex.
But the problems get even more complex. How about these two:
- The Superbowl Company produces footballs. Superbowl must decide how many footballs to produce each month. The company has decided to use a 6-month planning horizon. The forecasted demands for the next 6 months are 10,000, 15,000, 30,000, 35,000, 25,000, and 10,000. Superbowl wants to meet these demands on time, knowing that it currently has 5,000 footballs in inventory and that it can use a given month’s production to help meet the demand for that month. (For simplicity, we assume that production occurs during the month, and demand occurs at the end of the month.) During each month there is enough production capacity to produce up to 30,000 footballs, and there is enough storage capacity to store up to 10,000 footballs at the end of the month, after demand has occurred. The forecasted production costs per football for the next 6 months are $12.50, $12.55, $12.70, $12.80, $12.85, and $12.95, respectively. The holding cost per football held in inventory at the end of any month is figured at 5% of the production cost for that month. (This cost includes the cost of storage and also the cost of money tied up in inventory.) The selling price for footballs is not considered relevant to the production decision because Superbowl will satisfy all customer demand exactly when it occurs—at whatever the selling price is. Determine the production schedule that minimizes the total production and holding costs.
- General Ford (GF) Auto Corporation is developing a new model of compact car. This car is assumed to generate sales for the next 5 years. GF has gathered information about the following quantities through focus groups with the marketing and engineering departments.
- Fixed cost of developing a car: This cost is assumed to $1.4 billion ($1,400,000,000). The fixed cost is incurred at the beginning of the year, before any sales are recorded.
- Unit Gross Profit: GF assumes that in year 1, the gross profit will be $5000 per car. Every other year, GF assumes the unit gross profit will decrease by 4%.
- Sales: The demand for the car is the uncertain quantity. In its first year, GF assumes sales – number of cars sold – will be triangularly distributed with parameters 100,000, 150,000, and 170,000. Every year after that, the company assumes that sales will decrease by some percentage, where this percentage is triangularly distributed with parameters 5%, 8%, and 10%. GF also assumes that the percentage decreases in successive years are independent of one another.
- Depreciation: The company will depreciate its development cost on a straight-line basis over the lifetime of the car.
- Taxes: The corporate tax is 40%.
- Discount rate: GF figures its cost of capital at 15%
The general process is the same, of course, as the first two (decide how best to solve the problem, extract any essential information, determine what additional calculations they may need to do, then set up the problem and solve it), but these problems are even more complex because there is more information to extract, there are more calculations required that the students must perform (after they've figured out they have to perform them), the problems are more mathematically complex (the first requires linear programming and the second, a monte carlo simulation) and therefore the process to arrive at the solution is more complex, and unlike the first two, there are terms and concepts (sometimes with their own hidden calculations) students must know and understand: Planning horizon, inventory, demand, production and storage capacity, holding and production cost, production schedule, fixed cost (of developing a car, as opposed to fixed cost in general), unit gross profit, triangularly distributed (and parameters), depreciation (and straight-line basis), cost of capital, and NPV (net present value).
Then there is the covert information in the problem, such as "The fixed cost is incurred at the beginning of the year, before any sales are recorded," which actually is a hint on how to set up the problem, "The demand for the car is the uncertain quantity," which is another hint to tell students what the input variables for the simulation will be, "GF also assumes that the percentage decreases in successive years are independent of one another," another hint to tell students how to set up the problem. But students are poorly prepared in the problem-solving process (eek! another one of those hijacked phrases!) and many scan for numbers and ignore everything else.
See? I didn't even get to the mathematical knowledge required to know what additional calculations to set up, do them, or figure out how the information given fits together. But sure, they have to do that too. Solving a problem is much, much more than just coming up with the correct solution.
The only way to solve these problems without jumping off the roof of the nearest dormitory (actually yes, students do that -- I've had two students die during the semester, but neither committed suicide, I'm glad to say) is to approach the problem with the process that traditional math pedagogy has been teaching for several thousand years now. What kind of problem is it? What is the goal of the problem? What information is in the problem and what information is not in the problem? And so forth.
You can always tell the students in class who have been rigorously trained in formalism: They're the ones who immediately begin asking the questions and cutting it up into its components, and then solve it first, usually without much trouble at all. They read the problem and they know how to attack it. The students who have never mastered the thought processes behind solving problems are the ones that start then stop, start then stop, start then stop, and eventually give up, because they find it too frustrating just to try and get past reading the problem.
Friday, January 19, 2007
more shameless self-promotion
Sigh.
(Fixed the typo. That was embarrassing.)
Wednesday, January 17, 2007
vocational schools
Murray's article was rather lame. It read like an exam paper, hastily done at the the night before it was due.
Having said that, he does hit on one important point. There should be other options for people besides University. College is a ridiculously poor at training people for most jobs in the real world. As Murray points out, college has become little more than a litmus test for employers. My brother who is an electrical engineer for Boeing even admits that he maybe uses 10% of what he learned in college, and he has a Masters degree.
For many many jobs, specific technical schools would probably be a much more cost effective and efficient way to train new employees. Witness the U.S.A.F., that manages to train 18 -21 year old kids to work on multi-million dollar aircraft, with only a few months of formal schooling, and a year of on the job training. In my field, nondestructive inspection, 22 year olds are able to leave the Air Force after four years and get a job in the civilian sector earning $40,000 a year.
Having lived in Europe for 12 years, I think that many European countries take a much more pragmatic approach to post secondary education. For example, the German model has industries working in partnership with government to create Berufsschule's (vocational schools) that provide government certified certificates in over 400 different careers.
Moving to a system like this, or similar, would serve several purposes. Employers would get employee's with specific job knowledge, our college graduation rate should improve, and students without the desire to sit through four year's of irrelevant classes would be able to quickly move into the workforce.
Murray though doesn't do the idea much justice. It's as if he adopted it to make up for the political incorrectness of his research into the IQ gap. Of course, because of Murray's perceived political leanings, his suggestions will be ignored... but good ideas being ignored has become the norm in education policy these days, so why should this idea be any different.
(Cross posted at parentalcation)
Hat Tip: Joanne Jacobs