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← Back to Geometry
1Curved vs Straight Lines2Lines, Rays & Line Segments32D Shapes43D Shapes5Triangle Classification6Symmetry7Compound Perimeter

Concept 1 of 7

Curved vs Straight Lines

1

Today's big idea

A straight stroke never bends, so counting strokes tells you how a letter is built.

Counting strokes one at a time is what stops you missing the short ones.

2

How it works

👀 What's going on?

Trace the capital letter S with your finger. Your finger keeps bending the whole way. Now trace the letter I. Your finger goes in one direction and never turns.

💡 Here's the trick

E = 4 straight linesC = 1 curved line

Look at the two letters above. A straight stroke never bends, so the E needs 4 separate straight strokes to build it. A curved stroke bends smoothly all the way, so the C is drawn with just 1. Every letter, digit and figure is built from these two kinds of stroke.

🪄 How to do it

  1. 1.Look at the letter above and find where one stroke ends and the next begins.
  2. 2.Ask whether each stroke bends or stays straight the whole way.
  3. 3.Keep two separate counts, one for straight strokes and one for curved.

✍️ Try it

  1. 1.How many straight strokes make the capital letter T?
  2. 2.The word TOP is written in capitals. How many curved strokes does the whole word use?
  1. 1.T is one stroke across the top and one stroke straight down, so it uses 2 straight strokes.
  2. 2.T has no curve. O is one curved stroke. P is one straight stroke plus one curved bump. So TOP uses 2 curved strokes.

⚠️ Watch out

You might be thinking that a slanted stroke counts as curved, because it is not standing upright. It does not count as curved. Straight means the stroke never bends anywhere along its length. The two slanted strokes in a capital V lean hard, and both of them are perfectly straight.

🌟 Why this matters

Road signs, letters and shop logos are all built from these two kinds of stroke. Describing any of them starts with saying which kind each part uses. A designer who tells you a logo is 3 straight strokes and 1 curve has told you almost the whole design.
Exam tip: Class 3 olympiad questions often ask how many straight lines make a given capital letter.

3

Watch me solve one

Quanta solves it

“Watch how I think through one of these — then you try.”

THE PROBLEM

“How many STRAIGHT lines are used to make the letter 'K'?”

  1. 1

    Look stroke by stroke

    One line straight down, then two slanted arms. 〰️

  2. 2

    Count the straight strokes

    1 down + 2 slanted = 3 straight lines.

  3. 3

    Answer ✓

    = 3 straight lines

Now you try one — same steps, different story 👇

4

See it in action

⚡ Time to play!

Tap each straight stroke of the letter to count them.

STRAIGHT LINES · ROUND 1 OF 3 · LETTER T

Straight lines: 0
5

Quick check

✅ VERIFICATION

Which of these is drawn using ONLY straight lines?

⚡ Finish the activity above first to answer.

Keep going!

Up next: Lines, Rays & Line Segments

Segment · Ray · Line, count the dots and arrows.

Concept 2 of 7 →