# Parallel lines and Perpendicular lines

### Objectives

To enable students to-

1. understand the concept of parallel lines and perpendicular lines;
2. identify differences between parallel lines and non parallel lines;
3. understand about when two lines can be parallel (constant perpendicular distance)
4. to measure the perpendicular distance between two lines.
5. to provide hands-on experience through Geogebra application.

90 minutes

### Prerequisites/Instructions, prior preparations, if any

Prior understanding of lines and angles, right angle as 90 degree, use of protractor to measure/draw an angle.

### Materials/ Resources needed

• Digital : Computer, Geogebra application, projector.
• Non-digital : Geometrical tools, pencil and worksheet.

### Process (How to do the activity)

Teachers work:

• Show examples of pictures with parallel and non-parallel lines.
• Help students to identify their differences.
• Ask students on how they can conclude two line/segments are parallel and record the same.
• Introduce about the concept of perpendicular lines
• Help students understand that perpendicular line is the shortest distance between a pair of lines.
• Demonstrate using Geogebra how to plot parallel lines and check if perpendicular distance remains fixed between them.
• Ask students to give more examples of parallel lines in real life situations and their importance.

Students work:

• Identify the difference between parallel and non-parallel lines.
• Identify the parallel lines in their surroundings and measure the distance between them at various regions.
• Plot parallel lines using Geogebra and try to measure perpendicular distance between them.
• Plot perpendicular line using Geogebra and understand it as the shortest distance between two lines.
• Analyse the importance of parallel lines in real life situations.

### Developmental questions of the activity

1. When can we say two lines to be parallel and non-parallel?
2. What is the shortest distance between a pair of parallel lines?
3. What is the angle measurement of line drawn as shortest distance between the pair of parallel lines?
4. What is the length of the perpendicular line drawn at various positions between two parallel lines?
5. Where do you see perpendicular lines in our surroundings?
6. Where do you see parallel lines in real life situations? What is the importance of lines been parallel in them?

#### Application questions:

• Why are the rods of a window parallel?
• Why are the electric cables laid parallel to each?
• Can buildings have slant or perpendicular pillars? Why?
• Why are  Football stadiums rectangles?
• Why are  doors and windows usually rectangular?
• Why are some crops grown in fields parallel(example-cabbage)?
• Why we should not cross road diagonally?