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  • Maths
  • Class 5
  • 10 min
  • Medium

Letter Detectives

An L drawn with two straight strokes has a right-angle corner. A V has a narrow opening when drawn in its usual form. Longer names provide many places where straight strokes meet. Looking at these junctions turns familiar writing into an angle investigation.

Before you try

Would a rounded letter and a straight-stroke version contain the same corners?

Try it out

Interactive activity

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What happened?

Move a control to see what changes and why.

The game practises one idea at a time with simple drawn pictures. Check the same idea with real objects and your NCERT textbook (Chapter 2: Shapes and Angles, pages 25).

Try these ideas

  • Find right angles in a straight-stroke name.
  • Write the same name in a different style.
  • Mark an opening at a three-stroke junction before classifying it.

Why it works

An L drawn with two straight strokes has a right-angle corner. A V has a narrow opening when drawn in its usual form. Longer names provide many places where straight strokes meet. Looking at these junctions turns familiar writing into an angle investigation.

Some letters have three strokes meeting at one point. More than one angle can be described there, so a count is ambiguous unless the intended openings are marked. Letter Detectives uses circles and shaded openings. Count only those marked angles, even if you notice other corners in the name.

Changing the style of a letter can change its angles. A very wide V and a narrow V have different openings. A curved version may not have the same straight-line corners at all. When you write your own three names, use straight strokes, mark your chosen openings and explain your counting rule.

Worked example: You marked three right angles and two acute angles in a name. How many marked angles are there? Keep the counting rule: include only the marked openings. Add the two groups: 3 + 2. There are five marked angles. Unmarked junctions are not part of this count.

Check your understanding

Question 1 of 2

Which openings count in Letter Detectives?

Does changing a letter’s style sometimes change its angles?

Explain it in your own words

What changed? Why did it happen? Where might you notice this in everyday life?

What will you discover next?

Try Corner Carnival next.

Continue learning

For parents & teachers

  • Three-name notebook · 10 minutes. Write three names in straight strokes. Mark chosen right, acute and obtuse openings in different colours and make a count table.
  • Compare counting rules · 5 minutes. Two learners count the same marked name independently. If counts differ, point to each opening and agree on the rule.

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