Five Free Calculus Textbooks

Ben Crowell writes: "The economics of college textbooks is goofy, because the person who picks the book isn't the person who has to pay for it. Combined with the increasing consolidation of the publishing industry, this has blown the lid off of textbook prices over the last decade. But remember what the World-Wide Web was basically about before the Dot-Com Detour? It wasn't about marketing dog food, it was about democratizing publishing. Many textbook authors these days are using the internet to bypass the traditional publishing system, making their books available for free downloading. Although MIT's Open Courseware project gets most of the press, the movement started before that, and is going strong. In this article, I've reviewed five calculus textbooks that are either free as in speech or free as in beer." Read on for Crowell's take on each of the five books he's selected -- and pass the review on to any math teachers you know.

(See each)
author	(See each)
pages	(See each)
publisher	(See each)
rating	(See each)
reviewer	Ben Crowell
ISBN	(n/a)
summary	(See each)

First-Year Calculus Notes
author	Paul Garrett
pages	70
URL	http://www.math.umn.edu/~garrett/calculus/
rating	7/10
summary	Would make a good concise refresher.

The author provides this book in PDF format. As far as I can tell from the somewhat ambiguous notice on his web page, the book is intended to be licensed under the GPL copyleft license. That warms my heart as an open-source enthusiast, but it's slightly strange, for a couple of reasons. First, the GPL is a software license, and is less suitable as a copyleft license for books than the GFDL or a CC license. Also, the source code of the book isn't available (it appears to have been done in LaTeX), which I think makes it legally impossible under the GPL to redistribute the book, whereas the author's intent in GPL-ing it was presumably to make it freely distributable. Just as I was in the process of submitting this review to Slashdot, the author replied to an e-mail I'd sent him about this, and it sounds like he's interested in clearing up this issue, and really does want his book to be free as in speech.

This is a lively and very readable treatment of basic calculus. At 70 pages, it's a welcome antidote to the usual bloated textbooks, and the topics that are included match up pretty well with my own opinions of what it's really vital for a student to know after taking a calculus course. The tone is conversational without being condescending or cutesy, and the author almost always explains why he's introducing something, rather than just throwing it at the reader. (An unfortunate exception is the opening section on inequalities.) There is no attempt at rigor whatsoever, which I consider to be a feature, not a bug. Applications are discussed, although not enough for my taste (and I have to suppress my gag reflex every time I see a calculus book that insists on presenting the acceleration of gravity in non-metric units).

Although the book comes with some of the paraphernalia of a complete college textbook, such as homework problems, it's probably not the kind of book that another professor could just adopt as a stand-alone text, nor would I recommend it for someone learning calculus on her own for the first time. The title suggests that the author had in mind more of a memory aid, or a way to keep students from having to scribble madly in their notebooks for an hour and a half at a stretch. It lacks an index and illustrations, and there are some misfeatures in terms of organization: the chapters aren't numbered, and the homework problems are scattered around where they're hard to find. In some cases it sounds as though the first time a word or concept is used, he's assuming the reader has already heard it defined. I would, however, recommend this book to someone who needs to refresh her memory of calculus, and doesn't want to spend hours wading through epsilons and deltas to get to the highlights. It might also be a good option for the student who is completely broke, and needs a reference to use in place of an officially required text that carries an exploitative price tag. Although there are other calculus textbooks that can be downloaded without paying, this is the only one I'm aware of that follows the typical order of topics, and is also (AFAICT) copylefted, so that we can be assured it needn't evaporate if the author signs a publishing contract, or loses interest in maintaining his web site.

Difference Equations to Differential Equations: An Introduction to Calculus
author	Dan Sloughter
pages	600
URL	http://math.furman.edu/~dcs/book/
rating	6/10
summary	Takes too long to get there.

Like Garrett's text, this one appears to have been done in LaTeX, is licensed under the GPL, and appears to suffer from the same legal problems, because it's not available in source form.

The book is well written, and seems to have been well designed for practical classroom use. The approach is visual and intuitive, and there are lots and lots of graphs and numerical calculations. I felt, however, that it took a long time to get going, and the idiosyncratic selection of topics might make it difficult to use at many schools. Although the very first page gives a nice clear explanation of what calculus is about, we then have to wait until about page 136 to learn any calculus. I say "about" because of the inconvenient way in which the book is split up into 54 separate PDF files, each of which has page numbers starting from 1. I had to estimate page number 136 by weighing part of the book on a postal scale. Related to this problem is the fact that the book has no index or table of contents.

The book uses many numerical examples, which gives it a modern feeling . After all, calculus was invented by Newton and Leibniz because they needed to do calculations in closed form, but nowadays it's more natural to solve many problems on a computer, using a spreadsheet or a programming language. The book has a problem, however, in integrating the computer stuff with the didactic parts and the homework problems. No indication is given of how the numerical examples were actually computed. The author may consider it a trivial task to set up a spreadsheet or write a ten-line program in Python or Mathematica, but it's not so trivial for many students, and they will need extensive guidance from elsewhere to be able to carry out such computations for themselves. This makes the text incomplete in practical terms: any instructor wanting to use it would have to come up with extensive support materials to go with it. It also contributes to my sense that the book lacks focus. Students have a hard enough time learning the basic concepts and techniques of integration and differentiation, but to use this book, they would also have to learn about computer programming and difference equations. Adding to the bloat is the author's tendency to discuss every possible pathological case before moving on to the main event. It's a little like a parent trying to explain sex to his child, but feeling obliged to explain foot fetishes before getting on with where babies come from.

The examples that students are expected to do numerically also presuppose quite a bit of resourcefulness and insight. For instance, one of the homework problems asks the student to sum the series 4(1-1/3+1/5-1/7+...) numerically, adding up "...a sufficient number of terms to enable you to guess the value of the sum," which turns out to be pi. The trouble is that over 600 terms are required to get the sum to settle down in the second decimal place, which is about the minimum I'd want to see to convince me it was pi. Pity the poor student who first tries 10 terms on a calculator, then 50 terms on a spreadsheet, and then finally realizes he's going to need to write a Python program to get the job done. Of course, some students might enjoy the process, but my experience (teaching college science majors taking introductory physics) is that the majority don't consider computers to be fun.

Lectures on Calculus
author	Evgeny Shchepin
pages	143
URL	http://www.math.uu.se/~oleg/ShchepinCalc.html
rating	2/10
summary	Not for consumption by mere students.

This book is from a set of lectures on calculus given by visiting professor Evgeny Shchepin at Uppsala University in 2001. The first obstacle potential readers will encounter is that the book is provided in PostScript format, with hideous bitmapped type 3 fonts embedded. This makes it virtually impossible to view the book on a monitor in any legible representation, although it looks fine when you print it out. The typical Windows or MacOS user will give up long before that point. This is a shame, because it's not at all difficult these days to get LaTeX to output Adobe Acrobat files that are viewable on virtually any computer, and are legible on the screen. There is no index, and virtually no graphs or other figures.

The main question in my mind is for whom this book was written. This deep, dark forest of mathematical symbols, interspersed with ungrammatical English, is meant to follow the historical development of the subject, but it never makes it clear why the historical route is the right one to follow. There are many seemingly pointless digressions.

Is it possible that this book was meant for young people taking their first calculus course? The presence of end-of-chapter homework problems would seem to imply that it was. If so, I feel sorry for them. Although it's cute that the author manages to develop integrals before limits, and derivatives only at the very end, I somehow doubt that real, live students would read this book and exclaim, "We sure are lucky to be learning calculus using this novel order of topics!" Most of the problems begin with the words "Prove that...," and neither the text nor the problems give any of the standard applications to biology, economics, physics, etc.

Elementary Calculus: An Approach Using Infinitesimals
author	Jerome H. Keisler
pages	992
URL	http://www.math.wisc.edu/~keisler/calc.html
rating	10/10
summary	I wish I'd learned calculus from it!

Textbooks are usually unoriginal, because most teachers are conservative in their choices. They get used to teaching a subject a certain way, and don't want to change. This is a calculus textbook with a very unusual approach. It was published in 1976, and evidently was successful enough, despite its idiosyncracy, to justify a second edition a decade later. Its publisher, however, eventually allowed it to go out of print. The copyright has reverted to the author, and he has made it available in digital form on his web site. The digital book consists of pages scanned in from a printed copy and assembled into an Acrobat file, so it's a big download, and you can't do some things with it, such as searching the text for a particular word.

The title leaves no doubt that the book is different. Whereas most textbooks these days define derivatives and integrals in terms of limits, this one uses infinitesimals. The real numbers are generalized to make a number system called the hyperreal numbers, which include infinitesimally small numbers as well as infinitely large ones. Essentially, this represents a return to the way Newton and Leibniz originally conceptualized the calculus, but with more rigor.

I don't know about other people, but when I learned calculus, I got very uneasy when we got to the Leibniz notation. My teacher said that dy/dx wasn't really one number divided by another, but rather an abbreviation for the limit of the quantity y/x. That wasn't so bad, but what really made me queasy was when he then suggested that you could usually get the right answer by treating these dx and dy thingies as if they were numbers. The scary part was that word "usually." What was legal and what wasn't? How many sizes of infinitesimals were there? Was it legal to say that 1/dx was infinite? What operations would lead to paradoxes? What about proofs that used infinite numbers to show that 1=2? The wonderful thing about this book is that you end up knowing exactly what you can and can't do with infinities and infinitesimals, and you get to use the Leibniz notation in all its intuitively appealing glory. For instance, the chain rule really can be proved simply by writing (dz/dy)(dy/dx)=dz/dx, simply canceling the dy's.

It would be interesting to see how students reacted to this book when learning calculus from scratch. I suspect that they'd have an easier time with many of the concepts like implicit differentiation, which seems so awkward in the traditional approach, but they might be scared a little by the initial development of the hyperreal number system. The book develops the hypperreal system axiomatically, which left me yearning for more of a constructive method. Then again, we develop the rational and real numbers axiomatically in high school, so maybe it's not such a big issue. My initial unease was cleared up by a few crucial examples:

• If H and K are infinite, then H-K may be infinite or finite -- it depends on which infinite numbers H and K are.
• If H is infinite, then (2H+1)/(H+1) isn't equal to 2, but it differs infinitesimally from 2.
• (H+1)^1/2-(H-1)^1/2 is infinitesimal.

After that, I began to see the hyperreal numbers as simply another tool for calculating things.

I confess, however, to a little residual indigestion at the way the author develops the integral. He introduces finite Reimann sums first, and gives several numerical examples. But next, instead of taking the limit of sums with more and more terms, he takes the finite sum with n terms, and replaces n with an infinite integer. Instant vertigo!

This is a wonderful, original textbook, and I hope it remains free on the web forever -- it's not copylefted, so unfortunately it may disappear if the author stops maintaining his web site.

The Calculus Bible
author	G.S. Gill
pages	370
URL	http://www.math.byu.edu/Math/CalculusBible/
rating	3/10
summary	Incomplete, and badly written.

I'm reviewing this book in February of 2004. It's clearly not a finished product, and I'm not sure whether or not the author is still actively working on it. The book is available from the Brigham Young University math department's server, but the author isn't on the department's list of faculty, which makes me think he may have moved on to another job and abandoned the book. It's provided as a PDF file. There is no copyright page and no licensing agreement, so it's hard to know the book's real legal status.

The path through the topics is pretty standard for an introductory calculus course: a review of functions and trigonometry, followed by limits, differentiation, and integration. There is a good selection of problems, although to my taste as a physicist far too few are applied to anything useful. There is a table of contents, but no index. There are no illustrations; sprinkled throughout the text are little placeholders for graphs that just say "graph."

Although the problems I've referred to so far are ones that could be fixed if the author continued to work on the book, I feel that there are some more fundamental problems with this text that will not go away unless it is extensively rewritten. The style is extremely dry, and moreover the author has a habit of introducing concepts without any explanation or preparation. A symptom of this is that the student is expected to grind through the first hundred pages without any clear statement about what calculus is, what it's good for, or even whether the initial chapters are calculus (they're not). Equal prominence is given to topics that I would consider vital (the fundamental theorem of calculus) and others that I would label as trivial (tabulations of facts) or esoteric (the Dedekind cut property).

The Leibniz notation, dy/dx, is given with only this explanation "To emphasize the fact that the derivatives are taken with respect to the independent variable x, we use the following notation, as is customary..." Huh? So are these dx and dy things numbers? Is dy/dx the quotient of them?

Even if the missing graphs were included, the approach would still be relentlessly symbolic, rather than visual. For instance, integration by parts is introduced without ever giving its geometric interpretation.

Price != Quality

[elid]

A calculus textbook that costs $100 to buy doesn't mean it's worth a dime. My college used one of the more popular textbooks last year, and it was one of the worst textbooks I've ever encountered.

All I ask of a first year calculus book:

[bad enema]

- Lots of clear, thorough examples
- Minimize use of crazy symbols high school kids have never seen before. Or at least have a reference where you can look up what they mean.

That's all.

Re:Price != Quality

[tkajstura]

I agree. Many textbooks are used because of ties to the faculty of the deptartment. For instance, if a professor at a given university writes a textbook, and has a lot of say in what goes on in the deptartment, you can be sure that soon enough most other professors in the deptartment will be using their book. It's just the way university politics go.

Great, except...

[absurdist]

...for many professors, writing textbooks provides a serious boost to their salary. I had several courses in which the professor not only wrote the text, but made serious revisions every year in order to keep his revenue stream up. So not only could you not shop around to find a better price on a new text nor buy a used copy to keep your costs down, the resale value at the end of the semester was zip.

Re:All I ask of a first year calculus book:

[garcia]

- That the problems actually reflect what was "taught" in the examples.

I loved being "taught" what the examples showed and given a graded homework assignment only to find that 90% of the problems could not be solved with the given examples.

reviewer

[happyfrogcow]

Who is the reviewer and what is his math background? what made it possible for him to draw these conclusions for each book? Just curious. The conclusions I can draw from his reviews would vary depending on if I were receiving the insight of a university math professor, a grad student, a practicing engineer, a regular student, and so on...

Re:Price != Quality

[Rick the Red]

Yeah, but it was the textbook they required, so you had to buy it. None of these five alternatives would do you a damn bit of good when the Prof said, "Read pages 128-154 and do problems 3.15 through 3.24 by tomorrow."

Wheelock's Latin Grammar

[cardshark2001]

I took Latin in college, which was a mistake, but that's not what this post is about.

It's about the fact that every single year, Wheelock comes out with a new and improved Latin textbook, making the old ones obsolete, so that I couldn't sell mine back to the school store and recoup a small portion of my investment.

Now, when was the last time Latin grammar changed? About 1900 years ago? They could use Latin grammar texts from 50 years ago, and they'd be as good today as they were then. It seems to me that professors are complicit in this little scam.

The same goes for calculus. My calculus text was obsolete by the time I finished the course. Did calculus change? Did they put in some brand new groundbreaking stuff about measuring curves? No, they just wanted to make sure I couldn't sell back my book for others to buy more cheaply than the "new" one.

At the University of Texas, the cost of my books made up at least 30% of my total tuition costs. How insane is that? It's a racket, plain and simple.

Exactly.

[bad enema]

The assignment problems can't be solved with the given examples unless you're intelligent enough to extend your knowledge to the point where you can come up with a solution.

What ended up happening was we usually just copied off this one smart guy who did all the extending.

I guess T.A's are supposed to help you close the gap, but I would honestly have a few more difficult examples than a bunch of gimme exercises, which are always the ones the prof chooses to teach during lecture since they are the easiest and cause the least amount of confusion for the class.

Democratize publishing

[droo0g]

Publishing already is democratic, I think what the author was railing against was capitalism, which is another matter entirely. Granted, publishing companies have taken liberties with their content and their pricing structure. But what a good publisher brings to content delivery is filtering of garbage (which is what most of these free books are), quality editing, and a vehicle to reach a wide audience. Publishing books is expensive, the average profit margin for a text books is about %35, a lot less than the margin for jeans, sneakers or routers. If publishers learn to apply their knowlege to web delivery, which few have yet to do, then we may see quality content delivered on-line for a good price.

Re:Exactly.

[garcia]

yeah, they cause the least amount of confusion because they are already explained in the examples.

I am sorry, but at the Calc level I am unable to extrapolate the knowledge gained by 4 examples to cover 15 different problems.

It's been an issue with EVERY single Calc book I have seen (6 or 7 IIRC). Math books made for students by math professors. Really doesn't work too well.

Re:Books

[theparallax]

What does open source have to do with text books? I can't remember anyone compiling a calc book in the recent past. If you're talking about unlimited educational fair use, then please say what you mean and mean what you say. Let's not turn 'open source' into 'organic' or 'natural' or 'chemicals'.

Great review

[p3tersen]

Thanks for an interesting review! The economics of college textbooks are indeed a bit nuts, and the development of free (and especially libre) courseware is exciting. I gotta say though, if there's any course for which I think it's worth plunking down cash for a nice, well-bound, colour-printed book, it'd have to be first-year calculus. In particular I'm thinking of Stewart.

Another comment - most of these books seem to cover single-variable only - if you're going to need it eventually (as i did, being a physicist), i really think it's helpful to have vector analysis/differentiation/integration covered in the same book in a unified presentation. Again I'm thinking Stewart here.

I have read a dead-tree "calculus in order of historcal development" book before and it was a bit sticky but it was intended for more advanced maths or history-of-maths students... maybe that was the intended audience of the Shchepin book?

Re:Great, except...

[Tassach]

What's worse is when the professor uses your class as the beta test for his new book. That way you get to pay for the privilidge of proofreading his book for him.

I always hated taking classes where the professor wrote the book -- there was never any point in going to class, because everything they said in class was in the book verbatim. Call me idealistic, but I expect a professor to fill in the gaps the book leaves and to help me understand the difficult concepts.

'Calculus Made Easy' still a great book

[anandamide]

While not free, this little book does a great job of explaining the basics of calculus, what it's used for and how to visualize it.
Highly Recommended!
Amazon Listing [amazon.com]

Re:what is source? when is it open?

[p3tersen]

It's a finer line in the case of a math book though since the 'raw' text is written in a markup language called LaTeX that is essentally a programming language. You can write functions, scripts with if-then switches, etc. It's an intriguing question!

How about a F*#%ing English Textbook

[Anonymous Coward]

The economics of college textbooks is goofy, ...

Holy Jebus! Repeat after me, "Subject and verbs must agree.".

The economics of college textbooks are goofy, ...

The form of the verb "to be" must agree with the subject "the economics".

Now, let me click this anonymous checkbox in case I made any mistakes.

Re:See any serious problems with this story?

[orthogonal]

Yeah... it's an f'en review of five calc books. The author should be committed and never allowed to enter society again.

Me too ! I agree! Me too!

God forbid that anyone -- much less the readers of a site "for nerds [about] stuff that matters' should deviate from a steady diet of Star Wars, Tentacle Anime, and MMORGS.

Because it's more important to know the exact blue-prints of the X-Wing, Y-Wing and Z-Wing fighters than to understand physics -- and that the laws of physics don't actually allow the aerobatic maneuvers these fictional starships are depicted as making.

God forbid that we should know the calculus! Better we should be techno-peasants, with metaphorical manure between our toes, unable to comprehend the technical wizardry we gawp at in the movie houses.

The only reason we all have comparatively cheap PCs on our desks -- or the special effects that makes movies like Star Wars so absorbing (if inaccurate), or the ability to download Anime film or play MMORGS -- is because someone, lots of someones, took the time to learn the calculus -- and metallurgy, and materials engineering, and chemical engineering, and electrical engineering, and even computer science.

So before you "ban" the reviewer from society, please understand that the reason your sole amusement isn't getting chased by a wild boar as each of you tries to make the other lunch, is because of "dweebs" like the reviewer who care about the science and technology that created the society that allows you to have it so good and so easy.

Re:What is Calculus for?

[Professr3]

Without second-order differential equations to solve the spring-damper equations, your car would not have decent shock absorbers...

Re:Exactly.

[Anonymous Coward]

Exactly. A group of math professor's writing a math book are unlikely in their early 20s. They are likely well into their 30s and possibly even older. Sure, graduate students may have some minor input but based on my experiences with those that hold PhD's any sort of negative vibe they might get against their beliefs does not go over well.

So, a 30+ PhD (a master in their subject matter mind you) is going to teach me (a master of nothing) math? Remember, I don't have the mental capacity for math that they do and they expect things of me that shouldn't be expected.

Re:Hell hath no place in American primary

[gcaseye6677]

Honestly, I do not have a problem with this. The purpose of a textbook is to instruct a wide range of readers on a particular topic, not to provide an outlet for the author's free expression. I would certainly not be in favor of this type of standard for literary works, or for that matter in an English text which features reprints of actual stories, but for something that is strictly technical, the author's intentional and unintentional personal biases need to be removed. Textbooks are published to instruct, not for the author to make a statement.

Re:What is Calculus for?

[drgonzo59]

I would tend to disagree. It is rather a fault of the professors who taught Calc to fail to point out the practical uses of it, or at least the possible uses of it.

I never liked math much. I could figure it out, but physics, chemistry, comp. sci were more related to the world we live in. It was later in college when I had the painful realization that without math all those disciplines (and most others) are meaningless. I regret I had not put more effort into it then, that would have made my life much easier now. For example I took a Linear Algebra course in soph. year and after the exam week I had forgotten what an eigenvector was. It would have been nice for the prof. to point out the importance and the uses of it. Now I take a Quantum Computing course and I had to go back to the 4 year old dusty Linear Algebra notes for a review.

Re:"source code ... isn't available..."

[sloptaco]

also, pdf's and ps's are like binaries. LaTeX source code helps as a learning tool for people interested in mathematical typesetting. Not making this avaible would indeed be a gross violation of the GPL.

Re:All I ask of a first year calculus book:

[bfields]

I loved being "taught" what the examples showed and given a graded homework assignment only to find that 90% of the problems could not be solved with the given examples.

Sorry. As a calculus teacher, my job isn't to teach you a step-by-step program for, say, maximizing a smooth function of two variables with a unique maximum on an open interval. You don't have to understand a darned thing to do that.

My job is to teach you some underlying concepts, and to give you practice using those concepts as tools to solve a variety of problems.

This means that while I will give students lots of examples, explain concepts as clearly as I possibly can, and do everything to help, I will *always* assign problems that require fundamentally different solutions from the solutions given in any of the examples.

I've seen a lot of frustrated freshman who've learned over the years to do homework by skimming a chapter quickly (if at all) before looking for the example that gives them a template to solve the particular problem. You have to get past that.

--Bruce Fields

Re:Wheelock's Latin Grammar

[thisissilly]

You wouldn't expect to use a book based on 1700's english even though latin hasn't changed since then.

Funny, I had no problems reading The Autobiography of Benjamin Franklin [upenn.edu], even though it was written in the late 1700s. English hasn't changed that much. I think a Latin textbook from 1800-1922 would be perfectly acceptable, assuming it was a decent textbook to start with.

Re:Exactly.

[TopherC]

If you need 15 examples in order to solve 15 problems on some general topic, I might suggest that you haven't learned anything.

If solving a problem becomes a monkey-see, monkey-do type of excersize where you've been trained to use specific techniques on certain homework problems, then the student is practicing a technique but not understanding the subject. If the homework problems make the student think a bit and extend those "examples" in new ways, then they might be learning. Hopefully calc students expect that at the end of the course they can solve real-world problems that haven't been solved before, and apply the tools of calculus in ways that they haven't been explicitly taught. If they can't, then the entire course was a waste of time.

A good professor should be able to help any student gain this kind of working understanding of their subject, provided the student is also willing to work as hard as necessary. But there are a lot of professors out there that aren't that good. Since students don't often have much choice in the matter, they might have to look for help elsewhere.

Another problem is that students who have spent more time rehearsing techniques (recipies) and less time actually learning math tend to do better on timed, standardized tests. So to some extent the system punishes good students and teachers.

Re:GPL Abuse

[Anonymous Coward]

I have talked to a number of authors who applied the GPL to their products thinking that it simply made the binaries "free as in beer" and were shocked that I would ask for their source code.

The GPL is a very clear, very simple license. It's amazing that somebody would go to all the trouble of creating something, and then slap a license on it without even bothering to read it to make sure it is suitable.

Publishing democracy.

[fm6]

Hmm, I thought it was about, "Tim, we blew our damned budget on that NextStep cube, let's see you write some damned software for it!"

Seriously, Ben's pronouncements about "what the web is basically about" are both subjective and irrelevent. Whatever the early Web was about, it certainly wasn't distributing math texts. Which is why not a single one of the texts he reviews actually uses Web technology, except as way of copying a PDF or Postscript file from one computer to another. This is something you could certainly do without a Web, or even without an Internet.

The idea of "open source" textbooks strikes me as a pretty good one. But if you want to get the idea accepted, you should avoid both the simplistic pronouncements and the self-righteous finger pointing. I, for one, am deeply offended at implication that there's something wrong with using the web to buy and sell things. And if you want instructors to change the texts they require, you're not going to get their cooperation by accusing them of gouging their students, either through ignorance or greed.