STEP 1: SQUARE SHEET OF PAPER
- Ask the students to describe the shape. (E.g., the square has 4 sides. They are of equal length.)
- Observe that the opposite sides are parallel. They do not meet.
- The adjacent sides are perpendicular. They meet at a point. They meet at right angles.
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STEP 2: FOLD THE PAPER IN HALF (HORIZONTALLY)
- A new line segment is found.
- This new line is perpendicular to two of the sides. It meets them at a point each, at right angles.
- Now, there are three line-segments parallel to each other.
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STEP 3: FOLD THE PAPER IN HALF (VERTICALLY)
- This new line is perpendicular to the previous line.
- It also intersects the previous line. These two lines are called intersecting lines. The point where they intersect is called the point of intersection.
- Which are the parallel lines here?
- How many pairs of perpendicular lines can you identify?
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STEP 4: FOLD ALONG ONE DIAGONAL
- This line is neither parallel nor perpendicular to any of the previous, existing lines.
- It meets the lines from Fold (2) and (3) at the midpoint i.e., it intersects them.
- These lines are intersecting lines.
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STEP 5: FOLD ALONG THE OTHER DIAGONAL
- Is the new line perpendicular to any of the previous lines?
- Which are the intersecting lines?
- What is the point of intersection?
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