Geometrical Construction Understanding Geometric Lines: Construction and Application Basic Technology JSS 2 First Term Lesson Notes 5

Basic Technology JSS 2 First Term Lesson Notes Week 5

Subject: Basic Technology
Class: JSS 2
Term: First Term
Week: 5
Age: 12 years
Topic: Geometric Construction
Sub-topic: Lines – Identify and Draw Lines of Various Types
Duration: 40 minutes

Behavioural Objectives:

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

  1. Define geometric lines and their types.
  2. Identify and draw different types of lines.
  3. Perform bisection and division of lines accurately.

Keywords:

  • Line: A straight path extending in both directions with no endpoints.
  • Bisect: To divide into two equal parts.
  • Division of Lines: Splitting a line into specified segments.

Set Induction:

The teacher shows different types of lines in real life (e.g., roads, borders) and asks students to identify them.

Entry Behaviour:

Students may have basic knowledge of lines from previous mathematics lessons.

Learning Resources and Materials:

  • Rulers and protractors
  • Graph paper
  • Whiteboard and markers
  • Visual aids showing different types of lines
  • Video demonstrations of line construction

Building Background/Connection to Prior Knowledge:

Students have likely encountered lines in shapes and drawings before.

Embedded Core Skills:

  • Critical thinking
  • Collaboration
  • Problem-solving

Learning Materials:

  • Line identification charts
  • Reference books on geometric constructions

Reference Books:

  • Lagos State Scheme of Work
  • Basic Technology for Junior Secondary Schools by NERDC

Instructional Materials:

  • Rulers
  • Compasses
  • Markers
  • Graph paper

Content:

I. Definition and Explanation of Lines

  1. Definition: A line is a straight path that has no thickness and extends infinitely in both directions.
  2. Types of Lines:
    • Straight Line: A line that does not change direction.
    • Curved Line: A line that bends or curves.
    • Horizontal Line: A line that runs left to right, parallel to the horizon.
    • Vertical Line: A line that runs up and down, perpendicular to the horizon.
    • Diagonal Line: A line that slants or moves at an angle.

II. Uses of Lines

  1. Lines are used in drawings to create shapes and figures.
  2. They are essential in construction for accurate measurements.
  3. Lines help in navigation (e.g., maps).
  4. Used in graphic design to create visual interest.
  5. Important in diagrams for clarity in communication.

III. Bisection and Division of Lines

  1. Bisection: To bisect a line means to cut it into two equal halves.
    • Example: A line of 10 cm is bisected to make two lines of 5 cm each.
  2. Division: To divide a line means to split it into several parts.
    • Example: A line of 12 cm can be divided into four segments of 3 cm each.

15 Fill-in-the-Blank Questions:

  1. A straight line has ______ direction.
    a) No
    b) One
    c) Two
    d) Multiple
  2. A line that runs horizontally is called a ______ line.
    a) Vertical
    b) Straight
    c) Horizontal
    d) Diagonal
  3. Bisection divides a line into ______ parts.
    a) Equal
    b) Unequal
    c) Three
    d) Four
  4. Curved lines ______ change direction.
    a) Always
    b) Sometimes
    c) Never
    d) Rarely
  5. The point where two lines meet is called a ______.
    a) Segment
    b) Intersection
    c) Angle
    d) Line
  6. Lines used in navigation are often ______.
    a) Vertical
    b) Curved
    c) Straight
    d) Diagonal
  7. A line can be ______ into multiple segments.
    a) Measured
    b) Bended
    c) Divided
    d) Extended
  8. A diagonal line moves at an ______.
    a) Angle
    b) Straight
    c) Curve
    d) End
  9. The ______ of a line is essential in construction.
    a) Length
    b) Width
    c) Color
    d) Style
  10. A ______ is a line that runs up and down.
    a) Horizontal
    b) Vertical
    c) Diagonal
    d) Curved
  11. To divide a line of 8 cm into four segments means each segment is ______.
    a) 1 cm
    b) 2 cm
    c) 4 cm
    d) 8 cm
  12. Lines help in creating ______ in drawings.
    a) Shapes
    b) Colors
    c) Textures
    d) Patterns
  13. The symbol for a line segment is ______.
    a) A
    b) AB
    c) A-B
    d) AB-
  14. A line drawn with a ruler is considered ______.
    a) Straight
    b) Curved
    c) Broken
    d) Zigzag
  15. The process of drawing a line is known as ______.
    a) Measurement
    b) Construction
    c) Identification
    d) Division

15 FAQs with Answers:

  1. What is a line?
    A line is a straight path that extends infinitely in both directions.
  2. What are the types of lines?
    Types include straight, curved, horizontal, vertical, and diagonal lines.
  3. How do you bisect a line?
    You measure the line and mark its midpoint to create two equal segments.
  4. What is the use of horizontal lines?
    Horizontal lines are often used in graphs and drawings to represent stability.
  5. Why are lines important in construction?
    They provide accurate measurements and guide the layout of structures.
  6. Can lines be curved?
    Yes, a line can bend or curve, creating a curved line.
  7. What does it mean to divide a line?
    To divide a line means to split it into smaller segments of specific lengths.
  8. What is a diagonal line?
    A diagonal line slants at an angle between horizontal and vertical.
  9. How do you draw a straight line?
    You use a ruler to guide your drawing, ensuring it remains straight.
  10. What tools do you need for geometric construction?
    You need a ruler, compass, and protractor.
  11. Can a line have width?
    No, a line has no width; it is considered a one-dimensional object.
  12. What is an intersection of lines?
    An intersection is the point where two lines meet.
  13. Why are diagonal lines used in designs?
    They create visual interest and can indicate movement.
  14. What is the significance of line measurement?
    Accurate measurement is crucial for precision in various applications.
  15. How can I practice drawing lines?
    You can use graph paper to practice drawing different types of lines.

Presentation Steps:

Step 1:

The teacher revises the previous topic about materials used in geometric constructions.

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Step 2:

The teacher introduces the new topic by explaining the different types of lines and their uses.

Step 3:

The teacher allows pupils to contribute, asking them to identify examples of lines they see around them.

Teacher’s Activities:

  • Explain the definition and types of lines.
  • Demonstrate bisection and division of lines using a ruler and compass.
  • Facilitate group discussions on the importance of lines.
  • A point is defined as something which has a position and an extremely small magnitude so that it is barely visible. A point can be made on paper by a well sharpened pencil or a needle. A point is used to indicate position only, and in technical drawing it is usually represented by a cross or a dot.

    A line has position and length, but has virtually no thickness. A line may either be straight or curve. A straight is defined as the shortest distance between two points. Two lines are said to be parallel if they are always the same distance apart and cannot meet, however far they may be produced (extended) in either direction.

     

    ——————————–

     

    Types and Uses of Lines

    Lines are represented in drawings in various ways;

    Thick continuous lines are used for visible outlines and edges. The thickness of this kind of line is about 0.7mm. However, you do not have to measure the thickness of lines each time you draw. If you draw with a well-sharpened HB or 2Hpencil and apply a moderate pressure, you will produce a thick line.

    Thin continuous lines are used as dimension lines, projection lines, construction lines, and outlines of adjacent parts and resolved sections. They are also used as hatching lines. Thin lines are usually drawn with well-sharpened 3H, 4H or harder pencils with moderate pressure and resolved sections. They are also used as hatching lines.

    Thick long chain lines are used for cutting planes and viewing planes. They are also used ac centre lines, path lines and indicating movement, or extreme positions of movable parts, and for pitch circles. Like thick long-chain lines, thin long-chain lines, with thick ends may be used to indicate cutting planes.

    Thick continuous wavy or irregular lines are used for short break lines and boundary lines.

    Thin ruled lines with short zig-zags are used for long break lines.

    Thin continuous wavy lines are used for limits or partial views or for sections when the line is not an axis.

    Arrowheads are used at the ends of dimension lines. They are also used to indicate viewing planes and to indicate labeled parts. Arrowheads should be sharp, filled-in, and should be about 3mm long.

    TYPES OF LINES THEIR USES
     

    Thin continuous lines

    		 For dimension lines, projection lines and construction lines.
     

    Thick continuous wavy line

    		 For limits of partial waves.
     

    Thin ruled line with short zig-zags

    		 For long break lines.

     
     

    Thick continuous line

    		 For short break lines and boundary
     

    Thin long chain line

    		 For short break lines and boundary
     

    Thick long chain line

    		 For cutting and viewing planes as centre lines and path line for indicating movement.
    …………………………………..

    Thin short

    		 For hidden outlines and edges

    Construction of Lines and Angles

    Important guides to good construction;

    1. In technical drawing, all horizontal lines are drawn with the T-square and all vertical lines are drawn with a triangle (or a set-square) placed on the T-square.
    2. When drawing a line with the triangle, ensure that its edge rests firmly on the edge of the T-square.
    3. Always ensure that the edge of the stock or head of the T-square slides firmly on the left hand side edge (the square of the drawing board. The T-square should never be used to draw a line in any other position.
    4. Use well pointed pencils and take utmost care to draw lines through the required points, otherwise the result will not be satisfactory.
    5. In using dividers and compasses, avoid pressing the points deeply into the drawing paper, as this will cause in accuracy. Remember that a point has position only and should have no magnitude.
    6. In joining two points, adopt the following procedure: with the pencil point firmly placed on one point, slide the triangle up to meet it. Then swing the lower portion of the triangles until the lines up the other point on a straight-line with the first point. Check the second point for alignment by putting the pencil on point. Then draw the line joining the two points.
    7. There is no alternative to constant practice if you intend to draw accurately, neatly and fast.

    Bisection of Lines

    To bisect a given line;

    1. Draw the given line AB
    2. With centre A and any radius greater than half AB, draw the arcs above and below the line.
    3. With centre B, draw arcs of the same radius to cut the previous ones.
    4. The line is drawn through the intersections of the arcs.

    Division of Lines

    (A) To divide a straight-line into a number of equal parts;

    Suppose it is required to divide a straight-line 70mm long into 5 equal parts –

    1. Draw AB 70mm long.
    2. Draw AC at any convenient acute angle and set off from A, five equal divisions on this line using either a pair of dividers or a scale and pencil.
    3. Join point 5 to B using at 600 triangle. Through the other points draw lines parallel to 5B by sliding the triangle on any straight edge, such as a T-square.
    4. The line AB is divided into five equal parts by the line 1 – 1, 2 – 2, 3 – 3, and -4.

    Division of Lines in a Given Line Proportion

    Suppose it is required to divide a straight-line 9cm into four parts in the proportion of 2:3:7:4:

    1. Draw AB9cm long
    2. Draw line AC at a convenient angle and set off on it from A 2 + 3 + 7 + 4 = 16.
    3. Join point 16 to B. Through the point 12 = 2 + 3 + 7, 5 = 2 + 3, and 2 = 0 + 2 draw lines parallel to 16B. The parallel lines divide AB in the required proportion.

    ASSESSMENT

    1. What is the definition of a point?
    2. What are the steps in bisecting a line?
    3. Mention 5 guides in making good construction.
    4. List 5 types of lines.

     

     

Learners’ Activities:

  • Identify different types of lines in their surroundings.
  • Practice drawing various types of lines on graph paper.
  • Work in pairs to bisect and divide given line segments.

Assessment:

  1. Define a straight line and give an example.
  2. Explain the difference between horizontal and vertical lines.
  3. What does it mean to bisect a line?
  4. Provide two examples of curved lines in real life.
  5. How would you divide a 10 cm line into 5 equal parts?
  6. Describe a situation where you might use diagonal lines.
  7. What tools are needed for drawing geometric lines?
  8. Why is it important to draw straight lines?
  9. What property do all lines share?
  10. How can you check if a line is straight?
  11. What is the definition of a point?
  12. What are the steps in bisecting a line?
  13. Mention 5 guides in making good construction.
  14. List 5 types of lines.
  15. Give two examples of softwood and their uses.
  16. Give two examples of hardwood and their uses.
  17. List 5 uses of bronze
  18. List 4 types of brass
  19. What is the definition of a point?
  20. What are the steps in bisecting a line?
  21. Mention 5 guides in making good construction.
  22. List 5 types of lines.
  23. List 5 uses of brass
  24. List 5 uses of wood
  25. List 5 uses of metals

Conclusion:

The teacher goes around to mark the students’ work and provides feedback on their understanding of the topic.

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