STEM Club at Calvary Hills Baptist San Antonio

Schedule for 2025-2026

Sept 2025

20 rocks: sedimentary, metamorphic, igneous

27 international food tasting, locate the foods on a giant map

Oct 2025

4 continue int'l food tasting, what are special things about the countries?

11 microphones and mixer.  The directional microphone, the "shotgun" mic

18 student sharing, fun places to travel (but not theme parks).  Bring photos including on USB memory.

25 molecular models of stinky and poisonous chemicals.  DDT (clofenotane), mustard gas, trimethylamine (stinky fish smell), thioacetone (nearly the biggest stink! )   

Nov 2025

1 Engelbrechts on a trip

8 Engelbrechts still on a trip

15 solar furnace

22 microscope, also growing crystals

29 no class, Thanksgiving

Dec 2025

6 take your crystals home, also Rocks

13 Microsoft Flight Simulator and paper airplanes, grow crystals on strings

20 Van De Graaff and microwave-oven high voltage

27 no class, Christmas

Jan 2026

3 no class

10 chemistry

17 continue chemistry

24 the elements and Geiger counter

31 microscope

Feb 2026

7 electromagnets

14 Mr. Julio with cameras and lighting

21 art illusions, draw them yourself

28 the Solar System to scale, with Zoe

Mar 2026

7 no class, spring break

14 no class, spring break

21 power in electricity (resistors, transistors), measure degrees C with LM35

28 solar cells

Ap 2026

4 no class, Easter

11 Estes rockets (or prime numbers if rainy)

18 lenses and images

25 reaction time with Arduino and oscilloscope

May 2026

2 seed planting

9 soldering

16 speakers, little and big, this is the last meeting of the Spring

STEM Club on Saturdays, 10AM to 11:30AM

STEM can be fun, and we have what it takes to make it that way!  This is the STEM Club for your eager student.  Fun is important, but learning is our goal.  We partner with Calvary Hills Baptist.

Girls and boys, 2nd gr and older

Come when you can, no registration, free, ten seats (more if students pair up).  Visiting parent/child:  parent stays through the full session, but may go on errands (HEB, Walmart are close) if we have your contact information. 

Calvary Hills Baptist    910 W Loop 1604 N     North of Potranco at Loop 1604, north of Academy

Contact:  Mr. John at johnenge@earthlink.net      (512) 773-9266

Feb to May Topics 2025    Oct 12 2024 voting for topics

Feb 1 2025   solar furnace

Feb 8  Chemistry I

Feb 15  Chemistry II

Feb 22  Molecular Models or Estes Rockets

Mar 1  prime numbers or Estes Rockets

Mar 8  no STEM Club

Mar 15  no STEM Club

Mar 22  build audio amplifier with speaker to take home

Mar 29  Flight Simulator

Ap 5  finish audio amplifier

Ap 12  transistor:  amazing current amplification

Ap 19  No STEM Club

Ap 26  Van De Graaff generator and other voltages over 20,000 volts

May 3  No STEM Club

May 10  Last meeting for Spring.  Mrs. Aly presents about Big Bend National Park geology.

Jan 11  Sparks come from which electrical part?  Resistor Inductor Capacitor

Jan 18  Microscope and Magnifiers for bugs and plants

Jan 25  Microsoft Flight Simulator

Sept 14  Microsoft Flight Simulator if the computer is working

Sept 21  Pulleys and Levers, with ratio 

Sept 28  Soldering, melting tin/lead solder to make shiny electrical joints

Oct 5  Microsoft Flight Simulator including Cheat Mode, the newest fun thing to do to get right into Sea World and Fiesta Texas.  Add-ons for those waiting for Flight Sim:  the 3-D astronomy book with stereoscope, and cardboard tubes with plastic balls going through.

Oct 12  Medical Devices:  stethoscope, blood pressure cuff, mercury fever thermometers, the old style :^) , climb the stairs to make your heart beat fast, chart breaths per minute and heartbeat per minute after exercising, use computer spreadsheet to chart the results

Oct 19  Elements Day

Oct 26, Nov 2, Nov 9, Nov 16    Four sessions for motors:  DC, stepper, servo.  With Microsoft Flight Simulator for those who want to fly.   Nov 9 supplemental activity:  building molecular models for common substances, poisons, and stink.

Nov 23, 30  Mr. John and Mrs. Margaret go to a family funeral, then we take a Thanksgiving break.  No STEM Club on these days.

Dec 14   visit by professional photographer Julio with big cameras for us to use

sometime:  Molymod molecular modeling, especially poisons! (see below for details)      chemistry day      prime numbers day using factordb.com & Wolfram Alpha, amazing multiply problems that add up to all ones (333667 x 3 x 3 x 37,      333667 x 19 x 52579 x 7 x 13 x  3 x 3 x 11 x 37)        saturated hot solutions producing nice crystals         color filters, polarizer, spectrum, and spectroscope          HEB 16 bean soup mix, separate out the 16 types, predict which might sprout, plant in cups of dirt and find out      international food tasting (not STEM but fun, and spot on world map where foods come from)

Others to be voted on:

Motors (DC, stepper, servo),  Van de Graaff generator 80,000 volts,  Magnify bugs,  Chemistry,  Elements (as many as we can touch),  Solar Furnace and solar cells powering a motor,  Estes Rockets,  Python Coding,  Arduino Data Collection with charting,  Microsoft Flight Simulator,  Build and take home a regulated power supply 3 volt to 11 volt $11,  Inductor Day with Transformers (take home a little one you wind),  Resistor Day,  Audio Amplifier you take home with little speaker $9,  Mixer and Mics,  Volts Amps Watts Fuse,  Capacitor Energy Storage and Benjamin Franklin's improvement on the Leyden Jar,  Transistor $.09 as a current amplifier.

A higher grade of supplies and equipment, not toothpicks and marshmallows

• 8-channel mixer board and microphones, a "shotgun" mic

• Microsoft Flight Simulator for geography

• Molymod molecular modeling

• Real chemistry with stirring hot plate, test tubes, chemicals, distillation

• Oscilloscope, time measuring, distance & speed with gravity

• Soldering

• Ten PCs for math on Python, word processing, graphics with GIMP

• Arduino data acquisition

• Telescopes, binocular,  lenses

• Circuit board etching, soldering surface-mount parts to make circuits, transistors, LEDs, diodes

• Make capacitors and inductors 

• Motors:  DC, stepper, servo

• Pulleys

• DIY measuring/marking, scissors/saw, glue on cardboard and plywood, paint

Certified teacher/retired engineer John Engelbrecht and other adult leaders

STEM Club follows three years hosting Girls Who Code

You are looking at     sites.google.com/view/stem-club-west-san-antonio

Encouragement to Girls

Fifth-grade girls are better than boys in math and science.  But boys pull ahead of girls because boys naturally take risks, while girls in America are taught to be perfect and to decline opportunity if they aren't perfectly qualified.  Hewlett Packard found that men apply for jobs when they meet 60% of qualifications, while women don't seek jobs unless they are 100% qualified.  STEM Club follows the practice of Girls Who Code:  practice bravery by learning, experimenting, mixing success with failure, and collaborating to solve problems.   

Driving Directions

https://sites.google.com/view/girls-who-code-loop1604-west/gallery

Molymod Molecular Modeling, Ideas for molecules that are simple enough

Lower cost than Molymod is Old Knobby.

3-D structures for chemicals are at pubchem.ncbi.nlm.nih.gov.  The 3-D models may be rotated and zoomed to see the details.  Some students will like to do this.  Provide color code:  black carbon (diamond and graphite, graphite being just pencil "lead," graphite plus clay), red oxygen, blue nitrogen, white hydrogen, yellow sulfur

Mr. John took organic chemistry at age 40 and can interpret the shapes and bonding.

Molecule Day is livened up by offering 1) tasting of water, sugar, salt, butter, vanilla (diluted with corn starch), and cinnamon (diluted with corn starch).  Color these with food color as a disguise.

2) Some of the bad smells can be prepared ahead of time:  rotting meat, cabbage, garlic.  Ammonia is from some household sudsy ammonia.

3) Sulfur dioxide is made by burning some gardening sulfur.  The gas is poisonous if concentrated, just a whiff is enough.  The flame is a pale beautiful blue.

4) The fruit esters can be samples of fruit, best eaten with a wrapper of egg roll skin (HEB) to make it mysterious.

There is a lot more to do here than 75 minutes allows.  Pick and choose, do more on a subsequent molecule day.

Model these

water H2O      skunk is butane with SH added      cyanide deadly poison HCN     putrescine H2N-butane-NH2     cadaverine is putrescine with five carbons instead of four     ammonia NH3     sulfur dioxide SO2     salt NaCl     ant venom is formic acid HOCH with another O double bonded to the carbon 

glucose  is hexane with a lot of hydroxyls tacked on, hydroxyl is OH.  Look at pubchem for the structure.

butter or butyric acid   C C C C OH   with another oxygen double bonded to the carbon that has the hydroxyl.  The name for CO OH is carboxylic acid, where the first oxygen is double bonded to carbon.  Carboxylic acid shows up a lot, go ahead and use the name "Carboxylic acid."

vanillin is bigger, built on benzene

garlic, allicin   look at pubchem

cinnamic acid is benzene with this addition:  C C CO OH   the last O OH being carboxylic acid

methanethiol   rotten cabbage      H3 C S H

dimethyl disulfide  rotten garlic    H3 C S S C H3

Fruit esters are similar to each other.  These are simple enough.

   Raspberry, than add one carbon to get apple.  Pineapple is similar to apple.  

  Honey is benzene with an addition.  Strawberry adds one carbon to honey.

Microscope Day

microscope warnings (brain eating amoeba in pond water (wash hands), sharp glass slides), allowed controls

containers of pond water with spirogyra, students make well slides with cover slips & look for spirogyra and moving animals.  Also look with various magnifiers, with flashlights.  Wash hands for protection.

dead bugs with magnifiers

vote for ugliest bug from selection:  Usborne Complete Book of the Microscope cover & p. 55 fly head, p. 60 louse     Bodanis The Secret House p. 50 beetle, p. 63 ant, p. 211 bed bug

laptop pictures folder  microscope folder

A light microscope can't see atoms;  can barely see a square of a million atoms, 1000 atoms on a side.  Powers of Ten book.

dipping net demo on floor

Bible Minutes:  solder and circuits time line    2025 Feb 3       2025 May 21       2025 Nov  NSTA         Internet image:  human evolution ape to man  is wrong

Microsoft Flight Simulator in Calvary Hills Baptist Rm C2 has an always-on Internet connection (a requirement to fly the world, Microsoft maintains account verification while you fly, and if the connection is dropped there is on-screen notice of interruption, but it comes back in seconds) so that geographic, weather, and nearby aircraft information is always downloading.  A visiting Christian who has a retreat center in the Far East was thrilled to fly in his home city in the Far East.  If the following link, provided by Sh. Sc., works for you, listen at 53 seconds.              JE is able to close the Facebook sign-on window, then you are seeing the video.  Once you see the Facebook video, scroll down to see the audio mute button and enable audio.

https://www.facebook.com/share/v/9LCKTZqXq5YQGYxk/?mibextid=ox5AEW

Drama project by Classical Conversations

All Repeating Decimal Numbers are Really Fractions of Integers

https://sites.google.com/site/solderandcircuits/home/more-circuit-design/physics-timeline/physics-time-line-1900-1990/repunits-decimal-numbers-that-are-all-ones, scroll down about 15% to Document B, this is a graphic novel about the drama.

Classical Conversations is working to present the drama to IEEE Life Members Affinity Group of San Antonio, retired electrical engineers including several military vets and Southwest Research Institute people.  May 2025 meeting at La Fonda.  JE secured the program for this meeting.  

JE recently discovered that any fraction that has all nines, all threes, or all ones in the denominator will produce a tidy repeating decimal quotient, with the repeating part's length equal to the number of nines, threes, or ones in the denominator.     Repeating decimals are a sideshow to the repunits story.

To find interesting fractions that have repeating parts, and winnowing them down to ones that simplify a lot, making this a better math lesson, use this Python program.        It makes interesting use of Python modules to show 90 or more digits in a quotient, making it easier to spot repeating decimals, and reduce fractions to lowest terms.

# file  March 10 2025 finding fraction that has specific repeating part v5.py  JE

# ver3 extend to take advantage of Python fraction simplification

# ver4 calculate Fraction for every count

# ver5 shows smaller numbers that may reduce convincingly, has a control for more or less printing,

#  and is useful to scan thousands of numerators to find ones that reduce a lot

from decimal import *; from fractions import Fraction; import time

getcontext().prec = 60  # decimal module precision can be cranked up to hundreds, to reveal repeating decimals

count=0;  lenx=5; numx=10**lenx-1; printMore=False  # numx is all nines, nine times a repunit

small_digit_subtractor=0  #concentrate on zero for this variable, otherwise very long repeating parts

numxa=numx-small_digit_subtractor

for a in range(3799990, 3797130,-1):

    numy= a/(Decimal(numxa))

    if printMore: print('\ncount',count,'numerator',a, '  denom',numxa,' digits in denom',lenx, ', expect repeating group of',lenx,'.')#, numy ) 

    count += 1

    numyStr=str(numy)

    if printMore: print(Fraction(a,numxa),"is reduced to lowest terms by Python's fraction module.")

    frack=Fraction(a,numxa)  # reduces the fraction to lowest terms

    locSlash = str(frack).find('/')     # if location of the slash is followed by other than all nines or all threes, mark it

    count3=0;count9=0

    for d in range(locSlash,len(str(frack))-1):

        if str(frack)[d] == '3':  count3 += 1

        if str(frack)[d] == '9':  count9 += 1

    if (count3> (len(str(frack))-3 - locSlash)) or  (count9> (len(str(frack))-3 - locSlash)):

        if printMore: print('There are lots of 3 or 9 in reduced fraction')

    else:

        print('------------- the fraction reduced more than most',Fraction(a,numxa),a,numxa)

        if len(str(Fraction(a,numxa)))<0.7*(len(str(a))+len(str(numxa))): print('===the one above is really short========================')

        time.sleep(.03)    

    if printMore: print('The quotient char by char showing repeating group:')

    countPrt = 0

    for b in numyStr:   #this is done char by char

        if printMore: print(b,end='')

        countPrt += 1

        if countPrt % lenx == 0:

            if printMore: print('_',end='')

    if printMore: print('\n')

print('This repeating behavior in quotient is when denominator is all nines;  also for all threes or all ones.')

print('Reason for dividing by all nines:  it is the last step in finding the fraction (of integers) that')

print('  causes repeating digits in a quotient.  John Engelbrecht March 14 2025')

print('The code is file  March 10 2025 finding fraction that has specific repeating part v5.py')

print('This program runs a lot of consecutive (descending) numerators.')

print('You may copy-paste the num & denom into Wolfrom Alpha as a division; if there is a tidy')

print('  repeating part it will tell you the period of the repeat.')

# numerator 36740   denom 9999  digits in denom 4 , expect repeating group of 4 .# 3340/909 is reduced to lowest terms

# numerator 36720   denom 9999  digits in denom 4 , expect repeating group of 4 .# 4080/1111 is reduced to lowest terms

# numerator 36696   denom 9999  digits in denom 4 , expect repeating group of 4 .# 1112/303 is reduced to lowest terms

# 4179/11 3798711/9999

# 1557/41 3797523/99999

# 4672/123 3798336/99999