Where Did Paper Folding Puzzles Come From?
People have been folding paper for hundreds of years. Paper folding puzzles test your ability to picture what happens inside your mind. These puzzles show up on tests like the TACHS because they measure how well you can think about shapes and space. Let's look at how this idea developed over time.
So here's the big question these puzzles ask: If you fold a piece of paper, punch a hole through it, and then unfold it, where will all the holes be? Answering this correctly takes practice, but once you learn the rules, it becomes much easier.
Core Principles of Paper Folding and Punching
Before you try any problems, you need to understand a few key ideas. These rules work every single time, no matter how the paper is folded.
Symmetry Across the Fold
Layers Multiply Holes
Distance from the Fold Matters
Track the Fold Direction
Seeing It Step by Step
The diagram below shows a simple example. A square piece of paper is folded once from right to left. Then a hole is punched in the folded paper. Finally, the paper is unfolded to reveal two holes.
The key idea here is the fold line. It acts like a mirror. Whatever appears on one side of that line also appears on the other side, at the same distance away. In the diagram, the pink hole on the left is the same distance from the purple dashed fold line as the pink hole on the right.
How It Works — Counting Holes and Finding Positions
You don't need fancy math for these problems, but there is a simple counting rule that always works.
Finding the Position of Each Hole
To find where every hole ends up, work backward through the folds. Start with the punched hole on the folded paper. Then reverse the last fold and reflect the hole across that fold line. Keep reversing folds, one at a time, until the paper is fully open. Each time you reverse a fold, you double the number of holes.
What About Holes on the Fold Line?
If a hole is punched exactly on the fold line, something special happens. When you unfold, that hole does not create two separate holes. Instead, it stays as one hole right on the fold line. The two halves of the hole just open up into one larger opening. This is a tricky detail that test writers love to include!
Different Types of Folds
On the TACHS, you'll see several different fold directions. The diagram below shows the four most common types. Each one creates a different mirror line.
| Fold Type | Fold Line Direction | Holes per Punch |
|---|---|---|
| Left to Right (or Right to Left) | Vertical line down the center | 2 |
| Top to Bottom (or Bottom to Top) | Horizontal line across the center | 2 |
| Diagonal (corner to corner) | Diagonal line from one corner to the opposite | 2 |
| Two folds (any combination) | Two fold lines | Up to 4 |
Worked Example — Two Folds and One Punch
Let's work through a problem like the ones you'll see on the TACHS. Imagine a square piece of paper. First it is folded in half from right to left. Then it is folded in half again from bottom to top. Finally, a hole is punched in the upper-left area of the folded paper. What does the paper look like when it is completely unfolded?
Strategies and Common Mistakes
Knowing the rules is only part of the battle. You also need good strategies and you need to avoid the traps that test writers set for you.
| Strategy (Do This ✓) | Common Mistake (Avoid This ✗) |
|---|---|
| Undo folds in reverse order — last fold first. | Undoing the first fold first, which puts holes in wrong spots. |
| Count the folds to predict how many holes there will be. | Guessing the number of holes without counting layers. |
| Use the fold line as a mirror to find reflected positions. | Placing holes at random spots instead of reflecting them. |
| Check if any holes land on a fold line (these don't double). | Always doubling every hole, even when it sits on the fold. |
| Use scratch paper to draw it out if you're stuck. | Trying to do everything in your head on hard problems. |
Beyond the Basics — Multiple Punches and Complex Folds
Some harder TACHS questions will throw a curveball at you. Here's what to look out for as problems get trickier.
| Basic Version | Advanced Version |
|---|---|
| 1 fold, 1 punch | 2 folds, 1 punch (up to 4 holes) |
| Fold goes left-right or top-bottom | Diagonal fold (corner to corner) |
| 1 punch in the middle of the paper | Multiple punches in different spots |
| Hole is away from fold lines | Hole is on the fold line (doesn't double) |
| Square paper | Rectangular paper (changes proportions) |
When you see multiple punches, just treat each punch separately. Unfold each punch one at a time using the same mirror-reflection rules. Then combine all the holes together on one picture. The same rules always apply, no matter how complicated the problem looks.
Practice Problems
Try these five problems. They go from easier to harder. For each one, picture the folding and punching in your mind, then figure out the unfolded pattern.
Summary — Paper Folding and Punching
Paper folding and punching problems test your spatial reasoning — your ability to picture shapes in your mind. Every fold creates a fold line that acts like a mirror. Holes reflect across that fold line when the paper is unfolded. Each fold doubles the number of holes per punch, so one fold gives 2 holes and two folds give up to 4 holes.
To solve these problems, always undo folds in reverse order (last fold first). Use each fold line as a mirror to reflect holes to their matching positions. Watch out for holes on the fold line — these do not double. With practice, you can master these problems and boost your TACHS Ability score!