09 May 2000

Notes Prepared by Earl Zwicker

**ANNOUNCEMENT:**

Nobel Laureate in Physics and

Chair, Teachers Academy for Mathematics and Science

Monday, 22 May 2000

Perlstein Auditorium [33rd & State, NW Corner]

for a discussion about

**The Essential Transition from 19 ^{th} to 21^{st} Century
**

High School Science Education

buffet supper 6 pm

discussion 7 pm
**RSVP to (312) 567-8820 or parson@iit.edu**

OUR NEXT MEETING... ...will be the start of the Fall semester on September 5, Tuesday. You will receive a reminder in the mail. You may have registered already... SEE YOU THERE!!

**Mikhail Siddiq (Raymond School)**

asked, "Would you want $20,000 in cash, or 1 cent
doubled each day for 365 days?" Several people opted for
the cash until Mikhail showed us that on day 22 the
"income" would be $20,971.52, and the cumulative total by
that day would be $41,943.03!! Using a calculator, **Ken
Schug (Chemistry, IIT)** went to 46 days and got about
$1,470,000,000,000 ($1.47 trillion)! The power of
doubling! Amazing!

**Mamie Hill (Woods School)**

passed out large styrofoam cups, a piece of **Saran
Wrap ^{TM}** and a
section of comic strip. We cut off the top rim of the cup, taped the
Saran Wrap to the rim, then put a few drops of water on
the Saran Wrap which formed a lens-like shape. Using this
"lens," we could look through it and see the magnified
comic strip lying below. (Handout: Liquid Lens) What can
be learned from this? It may be used to view bugs and
other small things, and it's something students can
improvise at home and experiment further with it. A great
idea!

**Iona Greenfield (Carnegie School)**

gave out milk
cartons (8oz), popsicle sticks, sticky tape and
construction paper. From these materials we made
sailboats, using the bottom part of the milk carton for a
hull. The clay, stuck to the bottom of the "hull," held
the popsicle stick vertically to serve as a mast for a
sail made of the construction paper. With the sailboat
floating in a small tank of water, we could propel the
boat by blowing on its sail, and explore the answers to
various questions posed in the handout (Concept: **Moving
Air Can Do Work**). Hands-on science at work!

**Chandra Price (Burnham School)**

(handout: __Simple Science Experiments with Everyday
Materials__ by Muriel Mandell) passed out soda straws, each
enclosed in a sanitary paper wrapper. We tore off one end of
the wrapper, pushed down on the remainder to compress it to
about 1 inch in length, and removed it from the straw to
lay on the table. When we dripped a few drops of water
onto it, it GREW and writhed around almost like it was
alive! (Why?!) Chandra had several potatoes on the table,
and we found if we took a straw, and pushed it hard and
fast, it would go straight into a potato! Why didn't the
straw buckle or bend (as it does if we move the straw
slowly)? The entire straw has "inertia," the tendency of a
body in motion to continue in motion. Next, how can a
straw in an empty glass be bent without touching it? Add
water to the glass. It will appear to be bent where it
enters the water (refraction)! Try it! Then we
experimented with raw and hard-boiled eggs. How to tell
them apart? Just spin them. The raw ones slow down and
stop quickly, because the liquid inside absorbs the energy
of spin. Not so with the hard-boiled ones, since their
centers are spinning with the egg when set into rotation.
How to clean a penny? Soap and water doesn't work well, but
when we used a few drops of lemon juice, the penny got
nice and bright.

**Ken Schug** thought it was due to complexing **Cu ^{++}**
with citrate, which makes the copper oxide
on the surface soluble and it washes away. How to make an
egg float? Place it in a glass of water. It sinks to the
bottom. Add salt and stir. The salt water is more dense
than the egg, so the egg then floats. Finally, to some
milk in a cup, we added a little vinegar and stirred. The
acid vinegar denatures the milk protein to form curds, and
the clear liquid left is the whey. Lemon juice, being
acid, would also work. Great stuff, Chandra!

**Joyce McCoy (Spencer School)**

placed on the table: construction paper, markers, a stapler,
paper streamers (10 inch strips), and ribbon (10 inch). She gave
us handouts (Art Activities - Wind Sock), and showed us an
example, and we all got busy making our own take-home wind
socks. With a wind sock hanging outside a window, one can
judge how windy it is by watching how it behaves. The more
days you observe it, the better idea you have of how windy
it is! Neat!

**Barbara Baker (Doolittle West School)**

passed out a worksheet titled __All About Condiments__. And
then we each got several packets: (as from fast food restaurants)
ketchup, Dijon mustard, mayonnaise, duck sauce, honey, soy
sauce, sweet sour sauce. By reading the packets, we had to
write down their weights (units!), ingredients, and then
place the packet in a cup of water to see if it sinks or
floats. If it floats, it is less dense than water. And,
which condiment do you like best?

We were given another handout (Dinosaur Lessons), and a model for Pangea was constructed. Barbara had us tear a more-or-less round piece from construction paper (perhaps 7 inches diameter). Then we were invited up to the table where some pans (about 18 inches long) were partly filled with water. Barbara tore her round piece into 4 - 5 pieces, then carefully placed them on the water surface so they were back together again in their spherical shape. Then she dripped a few drops of a liquid detergent onto the paper, and the pieces rapidly moved apart from each other! A model of continental drift, and showing why dinosaurs could be found on different continents. Of course, the forces moving the paper "Pangea" apart in our model (surface tension forces) are not believed to be the same forces that produce continental drift on our planet Earth, but the analogy is otherwise a nice one, and it shows how the continents fit together like a puzzle to form one land mass, Pangea. See the website http://kids.earth.nasa.gov/archive/pangaea/. Thanks, Barbara!

**Kenneth Onumah (Kozminski Academy)**

passed out copies of graph paper on which students had traced
outlines of their hands and feet. One may count the
squares to estimate areas, and may graphically compare the
effects of age and gender by graphing points with a foot
dimension on the vertical axis against the corresponding
hand dimension on the horizontal axis. Ken showed us such
a graph, and the points showed a correlation in size,
meaning people with larger hands usually have larger feet.
Or one of those dimensions vs age, or vs gender. A most
interesting investigation, which motivates students since
they themselves are involved in a personal way!

**Marva Anyanwu (Green School)**

(handout: Monocots & Dicots) handed out monocot and dicot
seeds. We also received reproductive parts of plants with red flowers,
and could make comparisons with the information pictured
on the handouts. An active way to gain insight into
relationships in the world of the living!

**Pearline Scott (Franklin School)**

showed us some differences between a Math Fair
and a Science Fair. Both use poster boards, and scientific
method should apply in some form. Topics make take
somewhat similar forms; there are Math puzzles, games,
olympiads, and history. The Pythagorean Puzzle came up:

showed us puzzle pieces on the overhead and invited us to put them together to form a solid rectangle. And Roy Coleman (Morgan Park HS) showed the connection with the relation

Go to the website http://www.iit.edu/~smile/ph9711.html to find more on how the puzzle may be used, K-12, thanks to Harald Jensen.

**Earnest Garrison (Jones Magnet HS)**

told us how __Friends of the Chicago River__ test for water
quality. See the website
http://www.chicagoriver.org/ .
He gave us samples of various kinds of water to taste:

- Distilled water (tastes flat)
- Bottled water (not everybody likes it)
- Tap water (familiar)

**Estelvenia Sanders (Chicago Voc HS)**

did __Science in Sign XV__ for us: **Geometry for
the Deaf**. She educated us
about Tactile Interpreting (last time she did Cued Speech
with us). She made a sketch of an open left hand on the
board. With the thumb on the left, she wrote an A on the
top bone, and B on the bottom bone. The first (index)
finger was labeled C,D,E starting at the top bone and
ending at the bottom, then F,G,H for the middle finger,
etc. The letters of words can then be spelled out by
touching at the correct points on the fingers. Another
way, you can push your hand into theirs to form each
letter. Thanks, Estelvenia!

**Carl Martikean (Wallace HS, Gary)**

told us how to get information on a rocket launcher for an Air Impulse
Rocket or "Stomp Rocket." Go to the website
http://www.physics.purdue.edu/OUTREACH/rocket.html
Thanks, Carl!

MORE GOOD IDEAS!

SEE YOU IN SEPTEMBER!!

**Pokemon Cards, continued
Porter Johnson**

In a recent SMILE class **Patricia Phillips
[Arai Middle School]** posed
the question of how many __Pokemon Cards__ [given randomly and with
equal probability] one would have to get to have "reasonable assurance"
of having a complete set of 6 cards. We drew a few cards during the class,
and we able to confirm the claim that the "average" number drawn would be
about 14, and that you would generally have to get several of the same
kind before acquiring a full set.

The initial enthusiasm of getting the cards wore off after a few trials. I decided to "automate the process" by writing a computer program to do a significant number of "random trials". Here, for your potential amusement, is the FORTRAN program to make and record these trials:

c pokemon cards c monte carlo simulation c number of "draws" to get a complete set. dimension icard(6),ntimes(100), ncum(0:100) open(unit=8,file='poke.dat',status='unknown') c set up random number generator nrand = 11 call seed(nrand) c initializing counter of games to zero do 10 n = 1,100 10 ntimes(n) = 0 c input: number of games [complete sets] to get write(6,*)' how many games do you wish to play?' read(5,*) kgames write(8,88) kgames 88 format(' num games = ', i10) c playing the games do 100 k = 1,kgames c k is the game number do 40 i = 1,6 40 icard(i) = 0 c playing a particular game do 60 n = 1,100 c n is the number of cards in a given game call random(x) xx = 6.*x +1. j = int(xx) c j is the card number received on nth draw icard(j) = icard(j) +1 c icard(j) is number of times jth card has appeared t = icard(1)*icard(2)*icard(3)*icard(4)*icard(5)*icard(6) c testing for a complete set: t is not zero if (t.gt.0) then c complete set is obtained; go to next game ntimes(n) = ntimes(n)+1 goto 100 end if c end of a particular game 60 continue c if more than 100 games are required to get a match, we stop stop 100 continue c recording of write(8,*) ' number of draws for a match' write(8,99) (ntimes(n), n = 1,100) 99 format(10i8) c computing mean and standard deviation of number of draws sum1 = 0. sum2 = 0. do 200 n = 1,100 fn = float(n) fnum = float(ntimes(n)) sum1 = sum1 + fnum*fn sum2 = sum2 + fnum*fn**2 200 continue fgames = float(kgames) fmean = sum1/fgames fmeansq = sum2/fgames stddev = sqrt(fmeansq-fmean**2) write(8,999) fmean, fmeansq, stddev 999 format(' mean =', f10.6, /, ' meansq =', f10.6, /, > ' stddev =', f10.6) c ncum(n) is probability of getting a complete set after n games ncum(0) = 0 do 300 n = 1,100 300 ncum(n) = ncum(n-1)+ntimes(n) c print of ncum(j) write(8,*) ' cumulative hit number' write(8,99) (ncum(n), n = 1,100) c quit and go home stop end

Here is output for a run with ten million "games". In each game I told the computer to keep drawing until it got a complete set. A record of the number N of draws needed for each set is given, as well as the cumulative hit numbers [number of times that N draws or fewer is required to obtain a complete set]:

num games = 10000000 number of draws for a match 0 0 0 0 0 154776 385006 600803 750090 825776 843029 816335 762255 690521 613102 538025 466376 400611 342242 290821 245911 206988 174815 147081 122821 102982 85649 71363 60185 50199 41792 35076 29128 24394 20305 16716 14039 11830 9921 8163 6622 5673 4692 3953 3353 2869 2282 1943 1591 1315 1073 924 750 634 548 488 368 298 230 184 184 150 132 99 88 66 54 51 51 35 20 24 26 11 16 12 14 12 9 2 3 3 2 8 1 4 1 0 2 2 0 0 0 0 1 0 0 0 0 1 mean = 14.701120 meansq =255.126600 stddev = 6.245292 cumulative hit number 0 0 0 0 0 154776 539782 1140585 1890675 2716451 3559480 4375815 5138070 5828591 6441693 6979718 7446094 7846705 8188947 8479768 8725679 8932667 9107482 9254563 9377384 9480366 9566015 9637378 9697563 9747762 9789554 9824630 9853758 9878152 9898457 9915173 9929212 9941042 9950963 9959126 9965748 9971421 9976113 9980066 9983419 9986288 9988570 9990513 9992104 9993419 9994492 9995416 9996166 9996800 9997348 9997836 9998204 9998502 9998732 9998916 9999100 9999250 9999382 9999481 9999569 9999635 9999689 9999740 9999791 9999826 9999846 9999870 9999896 9999907 9999923 9999935 9999949 9999961 9999970 9999972 9999975 9999978 9999980 9999988 9999989 9999993 9999994 9999994 9999996 9999998 9999998 9999998 9999998 9999998 9999999 9999999 9999999 9999999 999999910000000

We see that the mean number of draws is about 14.70, whereas the spread in that mean is about 6.25, so that between 7 and 21 draws are required to get a full set most of the time. In fact, it is about 5.4 % probable to have a full set after 7 draws, about 51.4 % probable to have a full set after 13 draws, and about 87.3 % probable to have the set after 21 draws. However, the distribution of draws is quite "skewed", and the most likely number of draws required is 11, which occurs about 8.4% of the time. Of the ten million computer-generated games, one of the games required 100 draws to get a full set of cards.

The Monte Carlo approach to solving was first employed in large-scale
digital problems shortly after World War II by an applied mathematician
active in the Manhattan Project
Stanislaw Ulam, shortly after he
recovered from a very serious illness. There is no better introduction
to the subject than this paragraph, taken from his autobiography,
__Adventures of a Mathematician__, [U California Press 1991;
ISBN 0-520-07154-9] pp 196-197.

**
The idea for what was later called the Monte Carlo method occurred to
me when I was playing Solitaire during my illness. I noticed that it
may be much more practical to get an idea of the probability of the
successful outcome of a Solitaire game (like Canfield or some other where
the skill of the player is not important) by laying down the cards, or
experimenting with the process, and merely noticing what proportion comes
out successfully; rather than to try to compute all the combinatorial
possibilities which are an exponentially increasing number so great that,
except in very elementary cases, there is no way to estimate it. This is
intellectually surprising, and if not exactly humiliating, it gives one a
feeling of modesty about the limits of rational or traditional thinking.
In a sufficiently complicated problem, actual sampling is better than
examining all the chains of possibilities.
**

How do we understand these numbers, and how do we begin to compute the odds when the chances of drawing cards are not the same, as is surely the case for Pokemon cards given with Happy Meals at McDonalds?

Let us suppose that the pokemon cards #1, #2, #3, #4, #5, #6 are generated
with probabilities p_{1}, p_{2}, p_{3},
p_{4}, p_{5}, p_{6}, respectively. Each probability
p_{i} is positive, and the total probabilities must add to 1:

It is also true that

It is remarkable, but true, that if you write out the algebraic expression for

as a sum of monomials in p_{i}, the probability that,
in N draws, you get card #1 n_{1} times; card #2 n_{2} times;
card #3 n_{3} times; card #4 n_{4} times; card #5
n_{5} times; and card #6 n_{6} times, respectively, is
given by the monomial term occuring in the above expression; ie

where

n

in that polynomial, G

When the dust clears, we obtain the following expression for the probability of having a complete set after N trials:

- [p

+ [p

- [p

+ [p

-[p

In this expression the first line is complete; in the second line
there are 6 terms that involve any five of the p_{i}; in the
third line there are 10 terms that involve any four of the p_{i};
in the fourth line there are 15 terms that involve any three of the
p_{i}; in the fifth line there are 10 terms that involve any two
of the p_{i}; and in the sixth line there are 6 terms involving
each of the p_{i}. That is the answer, no matter what N is and
what the individual p_{i} happen to be.

We can simplify the answer considerably for the case in which the 6 cards
are equally probable, by setting p_{i} = 1/6. We obtain
that, for any N,

I have written an __EXCEL__ program to determine these numbers and to
draw a graph, which is shown below: The numbers agree with those obtained
in the Monte Carlo Simulation, to about four significant figures. Here
is a listing of the numbers for small values of N:

N | P(N) | N | P(N) | N | P(N) | N | P(N) | |||

1 | .0000 | 11 | .3562 | 21 | .8726 | 31 | .9790 | |||

2 | .0000 | 12 | .4378 | 22 | .8933 | 32 | .9825 | |||

3 | .0000 | 13 | .5139 | 23 | .9108 | 33 | .9854 | |||

4 | .0000 | 14 | .5828 | 24 | .9254 | 34 | .9878 | |||

5 | .0000 | 11 | .6442 | 25 | .9388 | 35 | .9899 | |||

6 | .0154 | 16 | .6980 | 26 | .9480 | 36 | .9915 | |||

7 | .0540 | 17 | .7446 | 27 | .9566 | 37 | .9930 | |||

8 | .1140 | 18 | .7847 | 28 | .9638 | 38 | .9941 | |||

9 | .1890 | 19 | .8189 | 29 | .9698 | 39 | .9950 | |||

10 | .2718 | 20 | .8480 | 30 | .9748 | 40 | .9959 |