Concept 1 of 8
Mirror Image: Left ↔ Right
Today's big idea
An upright mirror swaps left for right and leaves top as top, so b becomes d.
Letters whose halves match down the middle come back completely unchanged.
How it works
👀 What's going on?
Hold a page up to a mirror and the writing goes strange. Some letters survive it untouched and others turn into a different letter altogether, and which is which is not obvious until you look.
💡 Here's the trick
Look at the pair above. A mirror standing upright beside a letter swaps left for right and leaves top as top. That is why b turns into d and p turns into q, since the only difference between them is which side the bump sits on. Letters built the same on both sides come back unchanged.
🪄 How to do it
- 1.Picture the mirror standing upright beside the letter above.
- 2.Ask what is on the left and what is on the right, ignoring top and bottom.
- 3.Swap those two sides and read what you are left with.
✍️ Try it
What does a lowercase h become in an upright mirror? Then: does a capital H change at all?
The stem of h is on the left and the hump on the right. Swapping them puts the hump on the left, which is not a normal letter at all. Capital H is built the same on both sides, so it comes back exactly as it was.
⚠️ Watch out
You might be thinking a letter that looks tidy must be symmetric. Capital E looks tidy and is not, because all three arms point the same way and the mirror sends them the other way. Symmetry is about the left and right halves matching, not about looking neat.
🌟 Why this matters
Reading writing on the side of a van in your wing mirror, or on a shop window from inside, is this exact swap. It also explains why young children write b for d without being careless.
Exam tip: Test a letter by folding it down the middle in your head; if the halves match, the mirror changes nothing.
Watch me solve one
Quanta solves it
“Watch how I think through one of these — then you try.”
THE PROBLEM
“What is the mirror image of the lowercase letter ‘b’?”
- 1
Look at the letter
The letter b has its bump on the RIGHT.
- 2
Apply the mirror rule
Vertical mirror swaps LEFT and RIGHT. Top stays top.
- 3
Flip the bump to the LEFT
A letter with a bump on the LEFT is d.
- 4
Answer ✓
= d
Now you try one — same steps, different story 👇
See it in action
⚡ Time to play!
A vertical mirror swaps LEFT and RIGHT. Reveal the reflection, then name it.
MIRROR · ROUND 1 OF 3
Quick check
✅ VERIFICATION
Which capital letter is NOT the same as its mirror image?
⚡ Finish the activity above first to answer.
Keep going!
Up next: Water Image
Not to be confused with a side mirror, that flips left ↔ right.