Learn to convert units using the powerful cancellation method! With the right kind of practice, which this app provides, you will soon become as fearless as my own students (who use and enjoy this app!) when facing any units that need converting!
As shown below, this app takes a three-pronged approach:
Prong #1 (optional): Memorize 33 Handy Conversion Facts.
My personal top-33 list of unit conversions is presented in a series of four lists: weights, volumes, lengths, and a few extra. Zillions of conversion facts exist, of course, but these 33 have served me quite well as both an engineer and a technical math instructor. And although memorizing sounds like a chore, it's really nice to have a handful of facts you can spit out and use without having to pause to look something up!
If you accept the memorization challenge, a randomized quiz will help you determine which ones you really need to focus on. If you know a fact, leave it answered; if you don't, "unanswer" the question and you'll be asked again later.
Prong #2: Familiarize Yourself with the Cancellation Method.
The "lecture," so to speak, is split into four small screens, so you can digest one main thought at a time. You may wish to read the first couple of screens, practice with the first quiz, read a little more, practice with the second quiz, and so on. It will only take three practice quizzes to become an expert!
Another advantage to including notes, of course, is they'll help bring it all back to memory should you need a review in the future.
Prong #3: Visual Practice.
The visual quizzes are central to this app: They are designed to help you see what's going on and cement your understanding in minimum time.
The first quiz will require conversions in one or two steps. The second will include rates (like miles per hour) and could require up to three steps. The third and final quiz includes things like square feet and cubic inches, with each conversion requiring anywhere from one to four steps.
What's really cool is you can get by in life (at school, at work, and even in the garage) knowing only about 33 unit conversions! Indeed, part of what these visual practices are meant prove is that, when allowed to string a handful of facts together, 33 is indeed enough to do almost any conversion you want!
If this looks useful to you, please follow either link in the upper corners to download from the App Store (for both iPhone and iPad). At only a dollar, it's the next best thing to open source!