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← Parallel and Intersecting Lines

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Lesson 2 of 14

What parallel really means

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5 min

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Planks lie across the two rails. Every plank shows the same gap, the distance between the rails.

Two lines, both marked with the same arrow.
Step 1 of 4
  1. Two lines, both marked with the same arrow.
  2. Measure square across at spot A: 14 steps.
  3. Measure square across at spot B, far away: 14 steps.
  4. Try more spots. Same gap each time. The lines are parallel.

The rule

Lines on a flat page that never meet are called parallel lines. Arrow marks (>) on them show that they are parallel. Parallel lines also keep the same gap all the way along.

Measure square across: at a right angle to the lines. Do not measure on a slant. A slanted measurement is always longer than the square-across gap. So a slant would not compare two spots fairly.

Tap b or c. The lab checks with five gaps.

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Try the lab to finish this lesson.