Gas station without pumps

2014 September 10

edX finally finds the right market

Filed under: freshman design seminar,home school — gasstationwithoutpumps @ 10:02
Tags: , , ,

I have long been of the opinion that MOOCs are pretty useless for college students but are good for home-schooled students and high school students who don’t have access to higher-level courses in their local schools.  It seems that edX has finally realized that this is an important market with their High School Initiative:

Colleges and universities find that many students could benefit from taking a few extra courses to help close the readiness gap between high school and college. To address this need, edX has launched a high school initiative–an initial collection of 26 new online courses, including Advanced Placement* (AP*) courses and high school level courses in a wide variety of subject areas.

Completion rates will still be low, as a lot of people will sign up on a whim and then not follow through, or will sign up for more than they can handle and be forced to drop some.

AP courses will probably be the most attractive courses, as students can validate their learning with the AP exam, which is widely accepted by colleges as proof of higher-level course work (unlike the “Verified Certificate of Achievement” that edX sells).

The hardest courses to do well on line will be the lab science courses.  Simulated labs are no substitute for real-world labs, as no simulation captures all the phenomena of the real world and few come close to developing lab skills.

There are on-line science courses with real lab components. For example, my son took AP chem through, which had some rather cleverly designed labs that could be done at home with minimal equipment. Despite the cleverness of the lab design, the lab skills practiced were not exactly the same as would have been practiced in a more traditional lab setting.  And the lab kit was not cheap, costing as much as a community college chem lab course would have (if my son had been able to get into the over-subscribed chem lab course).

I don’t know whether edX has gotten their AP science courses audited by College Board (if not, they’ll probably be forced to remove the AP designation), but the AP audit requires lab time for the AP science courses, and I don’t know which of many mechanism edX is using to provide the required lab content.  Other online AP courses either devise home labs (requiring the purchase of a lab kit) or do weekend or week-long lab intensives in various parts of the country.  These lab intensives can be quite good (if done in college labs with real equipment) or ludicrously overpriced time wasters (if done in hotel ballrooms with crummier equipment and less time than the home lab kits).

The edX AP Physics course, created by Boston University, says “The course covers all of the material for the test, supported by videos, simulations, and online labs.”  So it seems that they have no real labs in AP Physics, but only simulations.  While simulation is a wonderful thing, it does not develop much in the way of real-world lab skills.  I note that in the freshman design course I taught last year, often the only experience that students had had in building anything had been in their high school’s AP Physics courses.  That hands-on experience is very important for developing engineers.

So the edX courses will be valuable for students who have no other access to AP-level material (which is a lot—fewer than 5% of US high schools offer AP Computer Science, for example), but students will still usually be better off finding a community college course or other way to real lab experience for the AP science lab courses.

I wish edX great success on this endeavor, since I have seen first-hand the need for reasonable quality, affordable courses for advanced high school students, which many local high schools cannot provide, because they do not have enough students ready for the course in one place to justify creating and offering the courses.  It is a much more worthy market than trying to compete with brick-and-mortar colleges, which was the initial goal of Coursera, Udacity, and edX.  Udacity has already abandoned that goal in favor of corporate training (again, a reasonable market).  It is good to see the edX is moving in a reasonable direction also.  When will Coursera realize that their original “disruptive” dream was a pipe dream (probably as soon as they’ve burned all the venture capital)?

2014 June 21

2014 AP Exam Score Distributions

Once again this year, I’m posting a pointer to 2014 AP Exam Score Distributions:

Total Registration has compiled the following scores from Tweets that the College Board’s head of AP, Trevor Packer, has been making during June. These are preliminary breakdowns that may change slightly as late exams are scored.

Disclaimer: I have no connection with the company Total Registration, and do not endorse their services.  If the College Board would collect Trevor’s comment themselves, I’d point that page.  The main interest in AP result distributions comes in May, when students are taking the tests, and July when the students get the results.

The official score distributions (still from 2013 as of this posting) from the College board are at, at least until the College Board scrambles their web site again, which they do every couple of years, breaking all external links.  They post a separate PDF file for each exam, which makes comparison between exams more difficult (deliberately, I believe, since inter-exam comparison is not really a meaningful thing to do).  It is also difficult to get good historical data on how the exam scores have changed over time—College Board probably has it on their website somewhere, but finding stuff in their morass is not easy.

Views for my 2011 AP distribution post show the May and July spikes.

Views for my 2011 AP distribution post show the May and July spikes. This has been my most-viewed blog post, which is a bit embarrassing, since it has little original content.

My 2013 AP distribution post has not been as popular, probably because of search engine placement at Google.

My 2013 AP distribution post has not been as popular, probably because of search engine placement at Google.

My most popular post this year was How many AP courses are too many?, with about 10 views per day.  (It has also come in third over the lifetime of the blog, behind 2011 AP Exam Score Distribution and Installing gnuplot—a nightmare.) The question of how many AP courses seems to come up both in the fall, when students are choosing their schedules, and in the spring, when students are overwhelmed by how many AP courses they took.

The one AP exam my son took this year was AP Chemistry, for which only 10.1% got a 5 this year and about 53% pass (3, 4, or 5). We won’t have his score for a while yet, so we’re keeping our fingers crossed for a 5.  He finished all the free-response questions, so he’s got a good shot at it.

The Computer Science A exam saw an increase of 33% in test takers, with about a 61% pass rate (3, 4, or 5). The exams scores were heavily bimodal, with peaks at scores of 4 and at 1.  I wonder whether the new AP CS courses that Google funded contributed more to the 4s or to the 1s. I also wonder whether the scores clustered by schools, with some schools doing a decent job of teaching Java syntax (most of what the AP CS exam covers, so far as I can tell) and some doing a terrible job, or whether the bimodal distribution is happening within classes also.  I suspect clustering by school is more prevalent. The bimodal distribution of scores was there in 2011, 2012, and 2013 also, so is not a new phenomenon.  (Calculus BC sees a similar bimodal distribution in past years—the 2014 distribution is not available yet.) Update 2014 July 13: all score distributions are now available, and Calculus BC is indeed very bimodal with 48.3% 5s, 16.8% 4s, 16.4% 3s, 5.2% 2s, then back up to 13.3% 1s. Calculus AB has a somewhat flatter distribution, but the same basic shape: 24.3% 5s, 16.7% 4s, 17.7% 3s, 10.8% 2s, and 30.5% 1s. Overall calculus scores are up this year.  The 30.5% 1s on Calculus AB indicates that a lot of unprepared students are taking that test.  Is this the “AP-for-everyone” meme’s fault?

Physics B scores were way down this year, and Physics C scores way up—maybe the good students are getting the message that if you want to go into physical sciences, calculus-based physics is much more valuable than algebra-based physics. I expect that the algebra-based physics scores will go up a bit next year when they roll out Physics 1 and Physics 2 in place of Physics B, but that the number of students taking the Physics 2 exam will drop a lot.  I don’t expect a big change in the number of Physics C exam takers—schools that are offering calculus-based physics will not be changing their offerings much just because the College Board wants to have more low-level exams.

AP Biology is still  seeing the nearly normal distribution of scores, with 6.5% 5s and 8.8% 1s, so there hasn’t been a return to the flatter distribution of scores seen before the 2013 test change.

As always, the “easy” AP exams see much poorer average scores than the “hard” ones, showing that self-selection of who takes the exams is much more effective for the harder exams. When College Board and the high-school rating systems push schools to offer AP, the schools generally start by offering the “easy” courses, and push students who are not prepared to take the exams.  As long as we have stupid ratings that look only at how many students are taking the exams, rather than at how many are passing, we’ll see large numbers of failed exams.

2013 August 26

I won’t teach chemistry

Filed under: home school — gasstationwithoutpumps @ 09:32
Tags: , , ,

As I mentioned in Homeschooling chemistry this year? “My son needs to take chemistry this year.  He doesn’t have much interest in the subject, …”

Since we couldn’t get him into the community college courses (the waitlist is still full), and the AP course at the local high school might let him in, if there was room, in the spring, it looked like I was going to have to learn it with him, like we did for physics.  While it would be good for me to learn general chemistry, I’m not sure I’m going to have time this year to give it the attention it would need.  I’m very afraid that we would slip on the schedule repeatedly, to my son’s detriment.

My son and I looked at online courses, and found one somewhat pricey one that seems to have gotten good reviews (not only in the customer testimonials, but also in one of the homeschool mailing lists, which tends to have less selection bias).  Although this is just AP chem (slightly less rigorous than the book I’d planned to use), we decided that the external schedule would probably be enough of a benefit to be worth the price to us.

The course is ChemAdvantage, taught by Peter Moskaluk.  It is costing me

$738.95 for tuition (with handling charges)

$239.45 for the chemistry kit (with shipping)

$16.98 for the textbook

for a total of $995.40.  If I decide to do the labs with him, I’ll need to get another pair of safety goggles, pushing the course over $1000.  That’s more than the community college would have been for 2 semesters, but a lot less than UCSC Concurrent Enrollment.  I would still have preferred the community college course, where he would have learned to use real chem lab equipment, but the California legislature has decided that education needs to be strictly rationed, so that they can continue to pay for imprisoning ever larger fractions of the population without charging corporations and wealthy individuals any taxes.

(Actually, I’ve already spent more than $1000 on the course, because I bought the new AP chem student lab manual, which we probably won’t have any occasion new to use, since the ChemAdvantage course comes with its own lab manual.)

I might still make a colorimeter, just for fun.


2013 August 13

Lab kits for homeschooling chemistry

Filed under: home school — gasstationwithoutpumps @ 10:10
Tags: , , ,

In my previous post, I mentioned the Advanced Microchemistry kit, from Quality Science Labs.

Another kit that has been mentioned in e-mail is one that I actually looked at earlier and forgot to include in yesterday’s post: the CK01 kit from the Home Scientist.  Instead of 16 labs, it is set up for 39 labs, and it costs only $174 instead of $220.  They also provide the lab manual on-line for free, so it is easy to see what the labs are and whether they are worthwhile.  They also do one other very clever marketing ploy—they sell the same kit for $5 more including a second set of splash goggles for the parent.  Since any sensible home school teacher will be nearby while the labs are being done, including a second set of goggles is just good sense.

Let me compare the 2 kits side-by-side:

Quality Science Labs,
Advanced Microchem
The Home Scientist,
acetic acid 0.1M acetic acid 6M
ammonia 6M
 ascorbic acid ascorbic acid (500mg tablets)
barium nitrate 0.1M
Bromothymol blue indicator Bromothymol blue 0.1%
calcium nitrate 0.1M calcium nitrate 0.1M
charcoal, activated
cobalt chloride moisture test paper (reusable)
copper copper
copper nitrate 0.1M
copper (II) sulfate 1M
distilled water
food coloring 0.1M
hydrochloric acid 0.1M hydrochloric acid 6M
iodine/iodide solution, 0.1M
iron (II) sulfate, 0.1M
iron (III) chloride, 0.1M
lead (II) acetate, 0.1M
magnesium sulfate magnesium sulfate
methyl orange, 0.1%
methyl red, 0.02%
nickel nitrate, 0.1M
oxalic acid, 0.5M
palmitic acid
pH paper wide-range pH paper
phenolphthalein paper phenolphthalein 0.5%
phosphoric acid, 1M
potassium bromide, 0.1M
potassium dichromate, 0.1M
potassium ferricyanide, 0.1M
potassium hydroxide, 0.1M
potassium iodide, 0.1M potassium iodide, 0.1M
potassium permanganate, 0.01M potassium permanganate, 0.1M
salicylic acid
sodium acetate, 0.1M
sodium bicarbonate (650mg tablet)
sodium bisulfite, 1M
sodium borate, 0.1% wrt boron
sodium carbonate, 1M
sodium ferrocyanide, 0.1M
sodium hydroxide, 0.1M sodium hydroxide, 6M
sodium salicylate, 220 ppm wrt salicylate
sodium sulfate, 0.1M
sodium sulfide, 0.1M
sodium oxalate, 0.1M
sodium thiosulfate 1.0M sodium thiosulfate 1.0M
starch indicator solution
sulfuric acid, 1M
thymol blue, 0.04%
turmeric reagent
vegetable oil
zinc nitrate, 0.1M
alligator clips 2 alligator clip leads
9v battery 9v battery
battery adaptor (9v)
15mL plastic beaker
30mL plastic beaker
(2) 50mL plastic beaker
(2) 100mL plastic beaker
150mL plastic beaker
50mL glass beaker
250mL borosilicate glass beaker
(6) 15mL centrifuge tubes
(6) 50mL centrifuge tubes
chromatography paper chromatography paper
coffee filters
conductivity tester
cotton swabs cotton balls and swabs
3 oz cup
8 oz foam cup, with cover
9.5oz plastic cup
digital scale
glass rod 15cm stirring rod
safety goggles safety goggles
10mL graduated cylinder 10mL graduated cylinder (plastic)
100mL graduated cylinder (plastic)
index card
1cc measuring spoon
paraffin wax
felt tip pen purple Sharpie felt-tip pen
graduated pipette graduated pipettes
thin stem pipette
mini pipette
24-well plate 24-well plate
96-well plate 96-well plate
rubber bands
6″/150mm ruler
steel wool
stop watch
spoon/spatulas stainless steel spoon/spatula
stoppers for test tubes
syringe 10mL oral, with cap
test tube 12×75mm (6) test tubes 16×100mm>
test tube brush
test tube clamp
test tube rack
digital thermometer
partial immersion thermometer
toothpicks wood splints
washing bottle
wire gauze wire gauze

The Quality Science Labs kit has some more expensive items (the digital scale, the multimeter, and the digital thermometer), but also includes more common household stuff and fewer chemicals. I already have a multimeter (better than what they provide), and a digital scale that measures to 0.01g is only $10. I’m not sure a digital thermometer is any better than the alcohol-based thermometers I already have (or that come in the other kit). If we need higher precision or to record over a time period, I already know how to set up a thermistor with the Arduino data logger.  The Home Scientist kit has somewhat more dangerous chemicals (higher concentrations of the strong acids and bases, for example).

Right now, it looks like the CK01 kit is the better buy for us, and I can read the manual to see if the experiments align with the new AP chem curriculum.

Neither kit provides a heat source, so we’ll either use the gas stove or buy a small alcohol heater to work outside.  We also need to get gloves, and various household supplies (like distilled water, distilled vinegar, …).  Both kits have a list of needed supplies—the list for the CK01 kit is much longer, probably because it is designed for twice as many labs.

Based on this side-by-side comparison, I think I’m more likely to get the CK01 kit.  It seems to have more of the stuff I’d need and less of the stuff that I already have.  I also like the marketing better (full details of the kit and the lab manual free on the web site).

2013 August 12

Homeschooling chemistry this year?

Filed under: home school — gasstationwithoutpumps @ 21:31
Tags: , , ,

My son needs to take chemistry this year.  He doesn’t have much interest in the subject, but one of his top choices for college (Harvey Mudd) requires entering freshmen to have had chemistry, and it would be easier to take it during the school year than to scramble to try to fit it in next summer.

Originally, we had planned for him to take a community college chemistry course, so that they could deal with the lab safety instruction, lab equipment, and proper disposal of chemical waste.  The community college course is perhaps a little lower level than what would be optimal for him pedagogically, but it is low cost and reasonably convenient.  Unfortunately, as a high school student he is among the last to be allowed to register, and by the time he was allowed to register not only were all sections of the chem class he needed filled up, but all the wait lists were also.  He could have gotten onto the wait-list for a lower-level chem class, but that would have gone painfully slowly for him, even if a slot opened up to let him register. So community college was out for us.

We heard that the local high school will sometimes let home-school students into AP courses (if there is room), but they have AP chem scheduled only for the second half of the year (the busier half for him), and their compressed schedule would require him to put about 1/3 of his attention on chemistry—something he’s reluctant to do.  Given the high probability that they would decide that their AP class is full, trying to use the local high school course seems too risky.

I considered having my son take Chemistry at UCSC, but that would be rather pricey at $5331 (not counting books or lab fees) as they stretch general chem out to 3 7-unit courses.  My son is also reluctant to committing to a 3–4-day a week commute up the hill for the entire school year.  I’ve also heard from some of the brighter students that the class goes very, very slowly—possibly because they have to pass more than 1000 students a year, many of whom have even less interest in chemistry than my son.

I looked a little at online courses, but none of them looked very promising.  Most were barely high-school level chemistry and quite a few seemed to be associated with young-Earth Creationist religious groups, which I will not knowingly support.  Even if there are some good ones out there, my son prefers books to videos, and most online courses are aimed at those who would rather watch than read.

So, it looks like I will be homeschooling chemistry this year, like I home-schooled physics for the past 2 years.  Unfortunately, I feel even less prepared for chemistry than I did for physics, so I’ll have to be learning general chemistry alongside my son. I have had only 4 chemistry classes in my life: a high-school chem class in 1968–69, a totally useless chemical thermodynamics without calculus class around 1975, a biochem class on replication, transcription, and translation before 2000, and a graduate protein structure class in 1998.  None of these prepare me for teaching a general chem course, and only the high-school chem class 45 years ago had any wet-lab component.  Increasing the challenge for me is that I’ll have very little time this year, with a higher-than-usual teaching load again this year. (I can’t really complain about it, since I volunteered to create a freshman seminar for the bioengineers WInter quarter—my chair even tried to talk me out of doing it as overload, though he recognized the need for the course.)

Over the summer, I picked up a textbook for free: Zumdahl’s Principles of Chemistry.  The chem department was discarding their TA copies of the old edition, since they are switching to a newer edition.  (The book is one of many that suffers from publisher churn—getting out a new edition every three years just so that students have to pay full price, rather than getting used copies of the book.)

I did a little checking on the web, and Principles of Chemistry seems to be a step up from Zumdahl’s Chemistry, which is commonly used for AP courses, which is in turn a step up from Zumdahl’s Introductory Chemistry, which is sometimes used for regular high-school chemistry.   I’m not sure where World of Chemistry fits in the collection of books.

I’m not sure I would have picked Principles of Chemistry as my first-choice text—it is almost 1100 pages not counting the Appendices and seems to written in a rather wordy style.  The book is packed full of gee-whiz sidebars and pictures and bios of famous (and not so famous) chemists.  I suspect that the actual content could be conveniently presented in a book a third the size.  But it is hard to argue with “free”, and it is a commonly chosen text for 1st-year college courses.

I still have to pick an order for covering the material, since the preface indicates that there are several chapters that can be presented in different orders: “the chapters on atomic theory and bonding (12–14), thermodynamics (9,10), and equilibrium (6–8) can be moved around quite easily.  In addition, the kinetics chapter (15) can be covered at any time after bonding.”  How I’m going to choose the best ordering for the material, when I don’t really know any of it, remains a mystery to me.

Of more concern to me is setting up appropriate labs.  I don’t think we really did enough labs in physics, and it was much easier for me to design physics labs and jury rig equipment than it will be for me to do the same in chemistry—so I worry about how we will do sufficient labs.  I joined the AP Chemistry teachers’ mailing list and asked for help there.

One teacher pointed me to Quality Science Labs, who make most of the chemistry kits that online courses use for their chem labs (they support Johns Hopkins CTY, Apex Learning, and ChemAdvantage, among others).  Their web pages did not enumerate what was in their kits, so I sent them a query, and they suggested their Advanced Microchemistry kit, which they say has been updated to align with the new AP Chemistry curriculum.  They also sent me a list of the contents of the kit and promised to put that list up on their web site.

The kit does not seem to include the experiments that are suggested for the new curriculum []:

Investigation 1: What Is the Relationship Between the Concentration of a Solution and the Amount of Transmitted Light Through the Solution?
Investigation 2: How Can Color Be Used to Determine the Mass Percent of Copper in Brass?
Investigation 3: What Makes Hard Water Hard?
Investigation 4: How Much Acid Is in Fruit Juices and Soft Drinks?
Investigation 5: Sticky Question: How Do You Separate Molecules That Are Attracted to One Another?
Investigation 6: What’s in That Bottle?
Investigation 7: Using the Principle That Each Substance Has Unique Properties to Purify a Mixture: An Experiment Applying Green Chemistry to Purification
Investigation 8: How Can We Determine the Actual Percentage of H2O2 in a Drugstore Bottle of Hydrogen Peroxide?
Investigation 9: Can the Individual Components of Quick Ache Relief Be Used to Resolve Consumer Complaints?
Investigation 10: How Long Will That Marble Statue Last?
Investigation 11: What Is the Rate Law of the Fading of Crystal Violet Using Beer’s Law?
Investigation 12: The Hand Warmer Design Challenge: Where Does the Heat Come From?
Investigation 13: Can We Make the Colors of the Rainbow? An Application of Le Châtelier’s Principle
Investigation 14: How Do the Structure and the Initial Concentration of an Acid and a Base Influence the pH of the Resultant Solution During a Titration?
Investigation 15: To What Extent Do Common Household Products Have Buffering Activity?
Investigation 16: The Preparation and Testing of an Effective Buffer: How Do Components Influence a Buffer’s pH and Capacity?

I can’t get the PDF for the AP chem lab manual (you need a password for that, which in turn requires passing an AP audit—too much paperwork for one student), but I will order the student lab manual in hardcopy, from the College Board store, like anyone else can. College Board charges $18 for the manual, $5 for shipping, and $2.01 for tax.  The tax amount is clearly wrong, since even here in California the sales tax is not (yet) 11.17%.

I think we may be able to do some of these labs: certainly I could hack together a phototransistor and an LED or laser diode to measure “amount of transmitted light”—that’s essential the same circuitry as the optical pulse monitor. Even the mechanical setup should be within my capabilities: drilling some holes through a block of wood to hold a test tube, the LED, and the phototransistor, like for my failed attempt at a pulse oximeter.

Instead  of the new AP labs, the microchem kit has 16 other labs [, available separately from the kit for $30]:

  • Lab 1 Gravimetric Analysis
  • Lab 2 Mole Ratios
  • Lab 3 Redox Titration
  • Lab 4 Electrochemistry: Galvanic Cells
  • Lab 5 Enthalpy of Fusion of Ice
  • Lab 6 Enthalpy of Reaction
  • Lab 7 Investigation Colorimetry: Light Path and Concentration
  • Lab 8 Types of Compounds
  • Lab 9 Paper Chromatography
  • Lab 10 Types of Chemical Reactions: Evidence for Chemical Changes
  • Lab 11 The Effects of Temperature and Particle Size
  • Lab 12 Analyzing Concentration vs. Time Data
  • Lab 13 Reversible Reactions
  • Lab 14 Solubility Equilibrium
  • Lab 15 Acid-Base Titration
  • Lab 16 A Buffer Solution

Some of these look like they overlap with the suggested AP labs (Investigation 1 and Lab 7, or Investigation 14 and Lab 15, or Investigation 16 and Lab 16).   I don’t know how “cookbook” the Advanced Microchem labs are—I need something that is straight-forward enough to be doable without a real chem teacher around, but not so routine as to be a pointless exercise.  Designing labs like that is tough, and from what I’ve heard, most first-year chem labs in college don’t succeed at it (being very cookbook).  Unfortunately, it does not look like Quality Science Labs sells the kit and the manual unbundled (you can get the manual without the kit, but not the kit without the manual), so I can’t really study the manual before buying the kit—at least not without wasting $30.

I’ll also need to buy some more safety equipment (another pair of splash goggles, probably some gloves).  I’ve been told that Flinn Scientific is a good source for high-school chem supplies (also Materials Safety Data Sheets and various teaching resources).

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