Lesson Notes By Weeks and Term v3 - Junior Secondary 3
Drawing of Plans and Blue-Print
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Drawing of Plans and Blue-Print
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Subject: Basic Technology
Class: Junior Secondary 3
Term: 3rd Term
Week: 2
Theme: Drawing Practice
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in terpret symbols on plans and blue-prints; identify the components of a building plan; draw and in terpret the plan of the ir classroom.
arrowheads and numerical values. Add dimensions for door and window openings and their distances from adjacent walls.
Step 6: Interpretation Teacher's Role: Guide students on how to read and understand information from a completed plan.
Student Activity: After drawing their plan, students should be able to interpret: The total number of doors and windows. The direction in which doors open (inwards or outwards). The relative positions of the chalkboard, teacher's desk, and student seating. The overall dimensions and area of the classroom (if calculating area is introduced). The orientation of the classroom relative to North. roof structure, showing slopes, drainage patterns, valleys, ridges, chimneys, vents, and any roof-mounted equipment.
Key Information: Roof pitch, materials (e.g., corrugated iron, asbestos, tiles), guttering, downpipes, position of water tanks or solar panels.
Relevance to Nigeria: Crucial for managing rainwater (especially during rainy seasons) and designing effective ventilation. 2.5 Drawing and Interpreting the Plan of a Classroom (Step-by-Step) This practical exercise will enable students to apply the concepts learned.
Step 1: Measurement Teacher's Role: Emphasize the importance of accurate measurements. Demonstrate proper use of measuring tape.
Student Activity: Measure the overall internal length and width of the classroom. Measure the width of the main door opening and its distance from the nearest wall. Measure the width of all windows and their distances from the nearest walls. Measure the dimensions and locations of any fixed features (e.g., chalkboard, built-in cupboards, teacher's desk position, specific columns). (Optional but recommended for detail): Measure thickness of walls, though for JSS3, a standard assumed wall thickness (e.g., 150mm or 6 inches) can be used.
Step 2: Scale Selection Teacher's Role: Explain the concept of scale (ratio of drawing size to actual size). Guide students to select an appropriate scale that allows the entire classroom plan to fit on their drawing paper (e.g., A4 or A3) while remaining clear.
Explanation of Scale: A scale of 1:100 means 1 unit on the drawing represents 100 units in real life. If a wall is 600cm long, it will be 6cm on the drawing.
A scale of 1:50 means 1 unit on the drawing represents 50 units in real life. If a wall is 600cm long, it will be 12cm on the drawing.
Example Calculation: Assume a classroom measures 9 meters (900 cm) by 7 meters (700 cm).
If using 1:100 scale: Length on paper = 900 cm / 100 = 9 cm Width on paper = 700 cm / 100 = 7 cm If using 1:50 scale: Length on paper = 900 cm / 50 = 18 cm Width on paper = 700 cm / 50 = 14 cm Students should convert all their measurements to the selected scale before drawing.
Step 3: Drawing the Outline Teacher's Role: Demonstrate drawing straight lines and accurate corners using a ruler. Emphasize consistency in line thickness.
Student Activity: Draw the outer rectangular (or polygonal) outline of the classroom walls according to the chosen scale. Draw the internal lines for wall thickness (if included, or simply represent walls as single lines for simplicity at JSS3).
Step 4: Adding Features Teacher's Role: Demonstrate drawing standard symbols for doors, windows, and other fixed features clearly on the board. Provide examples of common classroom elements.
Student Activity: Draw the classroom door(s) at their measured positions, using the correct symbol showing the swing direction. Draw the classroom window(s) at their measured positions, using the correct symbol. Add symbols for fixed features like the chalkboard, teacher's desk, and student desks (if they are permanently arranged). (Optional): Add symbols for light points, switches, or socket outlets if their positions were measured.
Step 5: Labelling and Dimensions Teacher's Role: Explain the importance of clear labelling, dimensioning, and providing essential drawing information.
Student Activity: Label the drawing clearly as "CLASSROOM FLOOR PLAN". Add the chosen scale (e.g., "SCALE: 1:100"). Draw a North arrow indicating the orientation of the classroom. Add overall dimensions (length and width of the classroom) using dimension lines with arrowheads and numerical values. Add dimensions for door and window openings and their distances from adjacent walls.
Step 6: Interpretation Teacher's Role: Guide students on how to read and understand information from a completed plan.
Student Activity: After drawing their plan, students should be able to interpret: The total number of doors and windows. The direction in which doors open (inwards or outwards). The relative positions of the chalkboard, teacher's desk, and student seating. * The overall dimensions and area of the classroom (if calculating area `[=]` 2.3.4 Plumbing Fittings: Kitchen Sink: A rectangular or oval shape, often with a double bowl indicated by a dividing line. Taps are usually shown as small circles.
Water Closet (WC) / Toilet: An oval or elongated shape representing the bowl, with a smaller rectangle behind it for the tank.
Shower: A square or circular shape, often with a cross inside to indicate the shower head.
Bathtub: A large, elongated oval or rectangular shape.
Example: WC: `[O]` (simplified)
Kitchen Sink: `[U]` (simplified with two taps) 2.3.5 Other Important Symbols: Stairs: A series of parallel lines with an arrow indicating the upward direction (UP) and number of risers.
North Arrow: A symbol (usually an arrow with 'N') indicating the geographical north orientation of the plan. This is essential for understanding sun path and wind direction relative to the building.
Dimensions: Lines with arrowheads and numerical values indicating lengths, widths, and distances.
Scale: Clearly stated ratio (e.g., 1:100, 1:50) showing the relationship between the drawing size and the actual size. 2.4 Components of a Building Plan A comprehensive set of building plans typically includes several types of drawings that provide different views and information about the structure.
1. Site Plan: Purpose: Shows the entire property boundaries, the location of the building(s) on the plot of land, driveways, walkways, landscaping, utility connections (water, sewer, electricity), and the surrounding context.
Key Information: Property dimensions, setbacks (distances from property lines), North arrow, contours (if applicable), existing and proposed structures, access points.
Relevance to Nigeria: Essential for urban planning approvals and understanding how a building fits into its compound or neighbourhood.
2. Floor Plan: Purpose: A horizontal "slice" through the building, typically at about 1.2 meters (4 feet) above the floor, looking downwards. It shows the layout of rooms, walls, doors, windows, fixed fixtures (like kitchen cabinets, water closets), and dimensions. Each floor of a multi-storey building will have its own floor plan.
Key Information: Room names (e.g., Living Room, Bedroom 1, Kitchen), wall thicknesses, door and window openings, overall dimensions, internal partitions, material indications (sometimes).
Relevance to Nigeria: The most commonly referenced drawing by homeowners and masons during construction of residential and commercial properties.
3. Elevations: Purpose: Exterior views of the building from each side (typically North, South, East, West elevations). They show the vertical dimensions, exterior finishes, roof lines, window and door placements, and relationships to the ground level.
Key Information: Building height, roof pitch, exterior materials (e.g., plaster, brick, stone cladding), window and door styles, details of verandas or balconies.
Relevance to Nigeria: Important for aesthetic design, material choices, and understanding the building's appearance from different directions.
4. Sections: Purpose: A vertical "slice" through the building, revealing its internal structure from foundation to roof. They show the relationship between different floor levels, roof construction, foundation details, and interior finishes.
Key Information: Foundation depth, floor-to-ceiling heights, roof structure (trusses, beams), wall construction details, level changes, and cross-sectional details of specific elements.
Relevance to Nigeria: Critical for structural engineers and builders to understand the structural integrity and construction methods.
5. Foundation Plan: Purpose: Shows the layout and dimensions of the building's foundation system, including footings, foundation walls, columns, and beams.
Key Information: Type of foundation (e.g., strip, raft, pad), dimensions of footings and foundation walls, reinforcement details, depth of excavation.
Relevance to Nigeria: Essential for ensuring the building's stability, especially given varying soil conditions across the country.
6. Roof Plan: Purpose: An overhead view of the roof structure, showing slopes, drainage patterns, valleys, ridges, chimneys, vents, and any roof-mounted equipment.
Key Information: Roof pitch, materials (e.g., corrugated iron, asbestos, tiles), guttering, downpipes, position of water tanks or solar panels.
Relevance to Nigeria: Crucial for managing rainwater (especially during rainy seasons) and designing effective ventilation. 2.5 Drawing and Interpreting the Plan of a Classroom (Step-by-Step) This practical exercise will enable students to apply the concepts learned.
Step 1: Measurement Teacher's Role: Emphasize the importance of accurate measurements. Demonstrate proper use of measuring tape. * Student Activity: This section provides a detailed explanation of the core concepts related to drawing of plans and blue-prints. 2.1 Definition of a Plan and Blue-Print Plan: In technical drawing, a plan is a scaled graphical representation of an object or structure as viewed from directly above (a "bird's-eye view"). It shows the horizontal arrangement and layout of elements. For buildings, a floor plan shows the arrangement of rooms, walls, doors, and windows at a specific level.
Blue-Print: Historically, a blue-print was a specific type of photographic printing process that produced white lines on a blue background, used for reproducing technical drawings. Today, the term "blue-print" is commonly used more generally to refer to any detailed technical drawing or engineering design document, especially for architecture, construction, or manufacturing, regardless of the colour of the paper or lines. It serves as the authoritative guide for construction or fabrication. 2.2 Importance of Plans and Blue-Prints Plans and blue-prints are indispensable in construction and design because they:
1. Serve as a Communication Tool: They provide a universal language for architects, engineers, builders, and clients to understand and agree upon design intentions.
2. Guide Construction: They provide precise dimensions, layouts, and specifications necessary for the accurate erection of structures.
3. Aid Cost Estimation: Detailed plans allow for accurate material take-offs and labour estimations, helping to budget projects effectively.
4. Ensure Safety and Structural Integrity: They specify structural elements, materials, and compliance with building codes, ensuring the safety and stability of the structure.
5. Facilitate Problem Solving: Issues can be identified and resolved on paper before costly construction begins.
6. Provide a Legal Record: Approved plans often serve as legal documents for permits and property records. 2.3 Interpretation of Symbols on Plans and Blue-Prints Symbols are shorthand representations of common building features and fittings. Understanding these symbols is crucial for interpreting any plan. 2.3.1 Doors: Representation: An opening in a wall, with an arc indicating the direction and extent of the door swing.
Types: Single Swing Door: A rectangle representing the door leaf, with an arc showing its 90-degree swing.
Double Swing Door: Two single door symbols side-by-side, swinging in opposite directions or outwards.
Sliding Door: A double line within the wall thickness, often with arrows indicating sliding direction.
Bi-fold Door: A zig-zag line indicating folding panels.
Example: ``` |----| | / | / | / |/ --- ``` (A simplified single swing door symbol) 2.3.2 Windows: Representation: Thin lines within a wall segment, often indicating the number of panes or type.
Types: Casement Window: Two lines representing the glass panes, often with small arcs indicating opening direction.
Sliding Window: Two or more lines overlapping, indicating panes that slide past each other.
Louvre Window: A series of thin, parallel lines representing the horizontal louvres.
Example: ``` |=====| | | | |=====| ``` (A simplified sliding window symbol) 2.3.3 Electrical Fittings: Light Points: Ceiling Light: A circle with a cross inside (e.g., for incandescent or fluorescent ceiling light).
Wall Sconce: A half-circle attached to a wall line.
Switch Points: Single Pole Switch: 'S' (or 'S1')
Double Pole Switch: 'S2' Three-Way Switch: 'S3' Four-Way Switch: 'S4' Socket Outlets: Single Socket Outlet: A rectangle with one line extending from the middle.
Double Socket Outlet: A rectangle with two lines extending from the middle. Power Outlet (e.g., for AC): A rectangle with a 'P' or 'AC'.
Example: Ceiling Light: `(x)` Single Switch: `S` Double Socket: `[=]` 2.3.4 Plumbing Fittings: Kitchen Sink: A rectangular or oval shape, often with a double bowl indicated by a dividing line. Taps are usually shown as small circles.
Water Closet (WC) / Toilet: An oval or elongated shape representing the bowl, with a smaller rectangle behind it for the tank.
Shower: A square or circular shape, often with a cross inside to indicate the shower head.
Bathtub: A large, elongated oval or rectangular shape.
Example: WC: `[O]` (simplified)
Kitchen Sink: `[U]` (simplified with two
This topic has strong practical relevance in the Nigerian context, connecting directly to daily life and local industries. Housing and Construction in Nigerian Communities: Application: Many Nigerian families aspire to build their own homes or renovate existing ones. Understanding plans helps them communicate effectively with local builders, masons, and carpenters. It enables them to interpret drawings provided by architects or draughtsmen, ensuring their vision is translated accurately into a physical structure. For example, knowing how to read a floor plan allows a homeowner to visualize room layouts, identify the location of key features like toilets and kitchens, and plan for furniture placement.
Local Context: Students can relate this to ongoing construction in their neighbourhood, understanding why some houses are built in certain ways, or why specific materials are chosen based on design. Community Development and Infrastructure Projects: Application: Knowledge of plans is vital for community leaders and citizens to understand proposals for public infrastructure projects such as new markets, primary health care centers, boreholes, or road networks. Understanding site plans helps in assessing the impact of a project on community land and resources, and floor plans help visualize the functionality of public buildings.
Local Context: Students can be encouraged to observe public construction projects in their towns or villages and consider how plans would have guided their development, from the layout of a new school block to the drainage system of a local market. Vocational Skills and Career Opportunities: Application: This topic serves as an introductory foundation for various technical and vocational careers that are highly relevant in Nigeria's growing economy.
These include: Draughtsmen/Draughtswomen: Professionals who prepare technical drawings and plans.
Architects: Designers of buildings and urban spaces.
Civil Engineers: Involved in the design and construction of infrastructure.
Builders/Contractors: Those who execute construction projects on-site.
Surveyors: Who map land and property, often producing site plans.
Local Context: Students who grasp these concepts well can be inspired to pursue technical education pathways at technical colleges, polytechnics, or universities, contributing to skilled labour in Nigeria's construction sector.