how to use this book
This is a learning experience, not a reference book. We deliberately stripped out everything
that might get in the way of learning whatever it is we’re working on at that point in the
book. And the first time through, you need to begin at the beginning, because the book
makes assumptions about what you’ve already seen and learned.
We don’t follow a regular school syllabus.
We couldn’t cover every single element of the syllabus so we paid attention to what
questions our own brains were asking, asked students what they found tricky, and we
included extra things which allow you to find patterns that link the learning together
because your brain loves patterns.
So, if you’re going to need to pass a test, then you’ll also need a reference book that covers
the syllabus for that test, but don’t worry. We’ve picked out the trickiest and most interesting
parts in this book, and we’ve emphasized understanding geometry so you should be in great
shape to slot those extra details into place quickly.
We don’t drag you through formal proofs of new concepts.
If you’re doing high school geometry you’ll probably be familiar with—and possibly
terrified of—geometry proofs. There are no formal proofs in this book. We believe
that, for most people, proofs make learning geometry harder than it needs to be. Instead,
we’ve used visual exercises to explore patterns and general rules in ways that we are
confident that you’ll remember and even be able to show other people.
We’re working on another book in this mini-series that will handle all that formal logic and
proof stuff, but for now you’re in great shape if you understand geometry in the real world
This is just about two-dimensional (2D) geometry.
We promise it’s not just so we can sell you another book called Head First 3D Geometry
soon! We’ve covered many of the most important techniques you’ll use when working in
two dimensions, so you’re all set for exploring further dimensions at the end of this book.
In fact, we’ve even snuck in a couple of 3D problems that you can work in 2D, because
geometry is about solving interesting problems in the real world, not just on paper.
We use plain English and not geometry jargon.
We believe your brain needs to see what something is, and figure out why you would
even care about it, before you can give it an unfamiliar label. We do use the geometry
jargon you’ll need to know for tests from time to time, but not until we’re sure you’ll know
what we’re talking about. We encourage you to use real words to describe patterns and not sweat
the official formulas too much.