Mathematics — Geometry

Subtopic: Lines (for 10-year-olds)

Lines are straight paths that go on. We use lines to draw shapes, measure distances and describe directions. You can see lines in everyday things: the edge of your classroom desk, the side of a book, the chalkboard edge or the edge of a door.

1. Important words

• Point — a spot. We name points with capital letters like A, B or C.
• Line — goes on forever in both directions. Shown with arrows at both ends.
• Line segment — part of a line with two end points. It does not go on forever.
• Ray — starts at one point and goes on forever in one direction. One end has a dot and the other has an arrow.
• Intersecting lines — lines that meet (cross) at a point.
• Parallel lines — lines that never meet. They stay the same distance apart.
• Perpendicular lines — lines that meet to make a right angle (like a corner of a book).

2. Simple pictures

3. How to draw lines (easy steps)

1. Use a ruler for a straight line. Put the ruler on the paper and draw along its edge.
2. To draw a segment, mark two dots (end points) and join them with a ruler.
3. To draw a ray, mark a dot for the start, then draw a line from the dot and add an arrow at the far end.
4. To show parallel lines, use the ruler and keep the same distance between the two lines.
5. To draw perpendicular lines, make a right angle using a set-square or match the corner of a book.

4. Examples you can find at school or home

• Edges of your textbook or copybook — straight lines and segments.
• Ruler marks — line segments.
• Window bars or the lines on a football pitch — parallel lines.
• Door frame and floor — perpendicular (they meet in a corner).

5. Try these activities (do them with your teacher or at home)

1. Draw a line segment PQ of length 6 cm. Label the ends P and Q.
2. Draw a ray RS that starts at R and points to the right. Put an arrow at the end.
3. Find two parallel lines in your classroom. Draw them in your book and write where you found them.
4. Find two perpendicular lines in your classroom (example: wall and floor). Draw and label their intersection point.

6. Quick questions (answers below)

1. What is the difference between a line and a line segment?
2. If two lines cross at a point, what are they called?
3. Are the opposite edges of a rectangular door parallel or perpendicular?

Good work! Practice drawing lines with a ruler every day. Ask your teacher to show you how to use a set-square for perfect right angles.