Mastering the Art of Lines in Technical Drawing SS 1 First Term Lesson Notes Week 4

Technical Drawing, SS 1, First Term, Week 4 on Lines (Types of Lines):

Lesson Plan: Types of Lines

Subject: Technical Drawing
Class: SS 1
Term: First Term
Week: 4
Age: 14-16 years
Topic: Lines (Types of Lines)
Sub-Topic: Identifying and Drawing Various Types of Lines
Duration: 40 minutes

Behavioral Objectives

By the end of the lesson, students should be able to:

1. Identify and name the various types of lines in technical drawing.
2. Correctly draw different types of lines (e.g., straight, dashed, dotted, thick, thin).
3. Differentiate between perpendicular and parallel lines and explain their applications.

Keywords

• Line
• Perpendicular
• Parallel
• Thick line
• Thin line
• Dashed line
• Continuous line

Set Induction

The teacher will ask students to recall their experiences in everyday life where they observe different types of lines, such as roads, windows, and construction sites, to create a link to the topic.

Entry Behavior

Students are familiar with basic concepts of drawing from previous lessons, including tools like rulers and pencils.

Learning Resources and Materials

• Drawing boards and pencils
• Rulers and set squares
• Sample drawings showing different types of lines
• Visual aids of parallel and perpendicular lines
• Chalk and blackboard

Building Background/Connection to Prior Knowledge

Students have likely seen and used different types of lines in everyday life and might have encountered basic drawings using lines in earlier subjects like mathematics.

Embedded Core Skills

• Precision and attention to detail in drawing
• Spatial awareness and geometric understanding
• Problem-solving skills in applying line types to design

Learning Materials

• Lagos State Scheme of Work for Technical Drawing
• Sample illustrations of perpendicular and parallel lines
• Drawings showcasing various line types (solid, dashed, thick, thin)

Reference

• Lagos State Scheme of Work
• “Technical Drawing” by Frederick E. Giesecke and Henry C. Spencer (for line types and applications)

Instructional Materials

• Visuals demonstrating types of lines: solid, dashed, dotted, thin, thick, etc.
• Demonstration materials (rulers, set squares)
• Examples of real-life applications of lines (e.g., floor plans, technical drawings)

Content Outline

1. Types of Lines:
   • Continuous Line: Used for drawing the edges of objects.
   • Dashed or Broken Line: Used to represent hidden edges or features not visible.
   • Dotted Line: Often used to indicate a boundary or imaginary line.
   • Thin Line: Used for light or less significant parts of the drawing.
   • Thick Line: Used for visible, important edges or outlines.
2. Perpendicular Lines:
   • Perpendicular lines are lines that intersect at an angle of 90°.
   • Common in technical drawings for right angles.
3. Parallel Lines:
   • Parallel lines are lines that run in the same direction and never meet.
   • Often used in architectural and engineering drawings for symmetry and alignment.

Fill-in-the-Blank Questions

1. A ______ line is used to show edges of visible objects in technical drawings (a. dashed, b. continuous, c. dotted, d. thick).
2. A line that represents hidden edges is called a ______ line (a. continuous, b. thin, c. dashed, d. thick).
3. ______ lines run in the same direction and never meet (a. parallel, b. perpendicular, c. diagonal, d. curved).
4. Perpendicular lines form an angle of ______ degrees (a. 30, b. 45, c. 60, d. 90).
5. ______ lines are typically used for outlining important features (a. thin, b. dotted, c. thick, d. dashed).
6. The ______ line is used to represent a boundary or imaginary line in drawings (a. continuous, b. dashed, c. thin, d. dotted).
7. A ______ line is used for light and less significant details in technical drawings (a. thick, b. dashed, c. thin, d. dotted).
8. Perpendicular lines intersect at ______ angle (a. 45°, b. 60°, c. 90°, d. 120°).
9. ______ lines are essential in showing symmetry and alignment in technical drawings (a. dashed, b. thin, c. parallel, d. thick).
10. To differentiate between parallel and perpendicular lines, one must check if the lines ______ (a. meet, b. are at 90° to each other, c. are drawn at different angles, d. have the same length).

Lines (Types of Lines)

Learning Objectives:

1. Identify Various Types of Lines and Their Applications:
   • Explanation: Lines are the fundamental elements of technical drawing. Different types of lines are used to convey various pieces of information, such as boundaries, measurements, and hidden features. Understanding the different lines and their uses is essential for creating accurate and understandable technical drawings.
   • Types of Lines:
     • Continuous Thick Line: Used to represent visible edges or boundaries of objects.
       • Application: Used to outline the outer edges of a building or machine part.
     • Continuous Thin Line: Used for drawing details and features that are visible but less prominent than the outer edges.
       • Application: Used for internal features of an object, such as door frames or internal walls in architectural plans.
     • Dashed (Hidden) Line: Represents edges or features that are hidden from view, typically behind another object.
       • Application: Used in mechanical drawings to show features like internal components of a machine that are not visible.
     • Chain Line (Centre Line): A line composed of alternating long and short dashes. It is used to indicate the center of an object or part.
       • Application: Used in floor plans to show the center of walls or for symmetry in technical drawings.
     • Dashed Thin Line: Used to represent hidden details, smaller than dashed lines, typically in mechanical and electrical drawings.
       • Application: Used for indicating hidden electrical components or pipes.
     • Phantom Line: A line used to indicate alternate positions of a moving part or the position of an object in the past or future.
       • Application: Used to show the movement of a door or a rotating wheel in mechanical drawings.
2. Draw Lines Correctly:
   • Explanation: Drawing accurate lines is crucial in technical drawing to ensure precision and clarity. Different lines require different techniques to achieve the correct weight and appearance.
   • Steps:
     • Use a ruler or T-square to draw straight, clean lines.
     • Vary the pressure on the pencil to achieve the desired thickness for different lines.
     • Ensure that lines are continuous where necessary and maintain uniformity in length and spacing.
   • Why it’s Important: Correctly drawn lines ensure the drawing is legible and accurate. Neat, consistent lines help communicate design details effectively.
3. Differentiate Between Perpendicular and Parallel Lines:
   • Explanation: Perpendicular and parallel lines are key concepts in geometry and technical drawing. Being able to distinguish between these types of lines helps in constructing and interpreting drawings.
   • Perpendicular Lines:
     • Definition: Lines that meet at a 90-degree angle.
     • Application: Used to represent right angles in architectural and engineering drawings (e.g., the corner of a building or a floor).
     • How to Identify: Perpendicular lines can be marked with a small square at the point where they meet.
   • Parallel Lines:
     • Definition: Lines that run in the same direction and remain equidistant from each other at all points, never meeting.
     • Application: Used to represent walls or boundaries that run alongside each other with equal spacing (e.g., parallel sides of a rectangular room or a road).
     • How to Identify: Parallel lines are marked by a series of equidistant dashes or with arrowheads at both ends in technical drawings.
   • Why it’s Important: Differentiating between perpendicular and parallel lines is essential for understanding the relationships between parts of a design. It ensures that structures, angles, and distances are accurately represented in technical drawings.