(This post originally appeared in Huffington Post’s Education section.)

Calculus. There, I said it. If your heart skipped a beat, you might be one of the roughly 1 million students–or the parent of one of these brave souls–that will take the class this coming school year. Math is already tough, you might have been told, and calculus is supposed to be the “make or break” math class that may determine whether you have a future in STEM (science, technology, engineering, or mathematics); no pressure huh?

But you’ve got a little under two months to go. That’s plenty of time to brush up on your precalculus, learn a bit of calculus, and walk in on day one well prepared–assuming you know where to start.

That’s where this article comes in. As a math professor myself I use several free to low-cost resources that help my students prepare for calculus. I’ve grouped these resources below into two categories: Learning Calculus and Interacting with Calculus.

**Learning Calculus.**

1. *Paul’s online math notes–an interactive website* (free).

This online site from Paul Dawkins, math professor at Lamar University, is arguably the best (free) online site for learning calculus. In a nutshell, it’s an interactive textbook. There are tons of examples, each followed by a complete solution, and various links that take you to different parts of the course as needed (i.e., instead of saying, for example, “recall in Section 2.1…” the links take you right back to the relevant section). I consider Prof. Dawkins’ site to be just as good, if not better, at teaching calculus than many actual calculus textbooks (and it’s free!). I should also mention that Prof. Dawkins’ site also includes fairly comprehensive precalculus and algebra sections.

2. *Khan Academy–short video lectures* (free).

A non-profit run by educator Salman Khan, the Khan academy is a popular online site featuring over 6,000 (according to Wikipedia) video mini-lectures–typically lasting about 15 minutes–on everything from art history to mathematics. The link I’ve included here is to the differential calculus set of videos. You can change subjects to integral calculus, or to trigonometry or algebra once you jump onto the site.

3. *MIT online lectures–actual course lectures in video format* (free).

One of the earliest institutions to do so, MIT records actual courses and puts up the lecture videos and, in some cases, homeworks, class notes, and exams on its Open Courseware site. The link above is to the math section. There you’ll find several calculus courses, in addition to more advanced math courses. Clicking on the videos may take you to iTunes U, Apple’s online library of video lectures. Once there you can also search for “calculus” and you’ll find other universities that have followed in MIT’s footsteps and put their recorded lectures online.

4. *How to Ace Calculus: The Streetwise Guide, by Colin Adams, Abigail Thompson, and Joel Hass* ($18.29 from Amazon.com).

If you’re looking for something in print, this book is a great resource. The book will teach you calculus, probably have you laughing throughout due to the authors’ good sense of humor, and also includes content not found in other calculus books, like tips for taking calculus exams and interacting with your instructor. You can read the first few pages on the book’s site.

**Interacting with Calculus.**

1. *Calculus java applets–online interactive demonstrations of calculus topics* (free).

There are many sites that include java-based demonstrations that will help you visualize math. Two good ones I’ve come across are David Little’s site and the University of Notre Dame’s site. By dragging a point or function, or changing specific parameters, these applets make important concepts in calculus come alive; they also make it far easier to understand certain things. For example, take this statement: “as the number of sides of a regular polygon inscribed in a circle increases, the area of that polygon better approximates the area of the circle.” Even if you followed that, text is no comparison to this interactive animation.

One technological note: Because these are java applets, some of you will likely run into technology issues (especially if you’re on a Mac). For example, your computer may block these applets because it thinks that they are malicious. Here is a workaround from Java themselves that may help you in these cases.

2. *Everyday Calculus, by Oscar E. Fernandez* ($13.99 to $18.60 from Amazon.com).

Self-promotion aside, calculus teachers often sell students (and parents) on the need to study calculus by telling them about how applicable the subject is. The problem is that the vast majority of the applications usually discussed are to things that many of us will likely never experience, like space shuttle launches and the optimization of company profits. The result: math becomes seen as an abstract subject that, although has applications, only become “real” if you become a scientist or engineer.

In *Everyday Calculus* I flip this script and start with ordinary experiences, like taking a shower and driving to work, and showcase the hidden calculus behind these everyday events and things. For example, there’s some neat trigonometry that helps explain why we sometimes wake up feeling groggy, and thinking more carefully about how coffee cools reveals derivatives at work. This sort of approach makes it possible to use the book as an experiential learning tool to discover the calculus hidden all around you.

With so many good resources it’s hard to know where to start and how to use them all effectively. Let me suggest one approach that uses the resources above synergistically.

For starters, the link to Paul’s site takes you to the table of contents of his site. The topic ordering there is roughly the same as what you’d find in a calculus textbook. So, you’d probably want to start with his review of functions. From there, the next steps depend on the sort of learning experience you want.

1. If you’re comfortable learning from Paul’s site you can just stay there, using the other resources to complement your learning along the way.

2. If you learn better from lectures, then use Paul’s topics list and jump on the Khan Academy site and/or the MIT and iTunes U sites to find video lectures on the corresponding topics.

3. If you’re more of a print person, then *How to Ace Calculus* would be a great way to start. That book’s topics ordering is pretty much the same as Paul’s, so there’d be no need to go back and forth.

Whatever method you decided on, I still recommend that you use Paul’s site, the interactive java applets, and *Everyday Calculus*. These three resources, used together, will allow you to completely interact with the calculus you’ll be learning. From working through examples and checking your answer (on Paul’s site), to interacting directly with functions, derivatives, and integrals (on the java applet sites), to exploring and experiencing the calculus all around you (*Everyday Calculus*), you’ll gain an appreciation and understanding of calculus that will no doubt put you miles ahead of your classmates come September.