Lesson Note on Sections: Interpretation of sectioning, Production of sectioning for SS 2

Class: Senior Secondary School 2 (SS2 / SSS2)
Term: 1st Term
Week: 5
Age: 16 years
Duration: 45 minutes
Subject: Building Construction
Curriculum Theme: Technical Drawing and Building Technology
Previous Lesson: Sections: Sectioning, cross and longitudinal sections.
Topic: SECTIONS
Subject Matter: Interpretation of sectioning (how to read and understand sections), Production of sectioning (how to produce correct sections)

Specific Objectives

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

Cognitive Domain:

• Define sectioning in building construction.
• Identify and differentiate between cross-sections and longitudinal sections.
• Explain the importance of sections in building design and construction.

Affective Domain:

• Appreciate the need for accuracy in interpreting and producing sectional drawings.
• Show interest in learning about different types of sections.

Psychomotor Domain:

• Interpret a given sectional drawing to understand building components.
• Produce simple cross-sections and longitudinal sections from plans and elevations.

Social Domain:

• Collaborate with peers to discuss and understand sectional drawing principles.

Reference Materials

The following resources were used in planning this lesson:

• Senior Secondary Schools Education Curriculum
• State Unified Scheme of Work
• Oyebola, A. (2018). Building Construction for Senior Secondary Schools. Ibadan: Evans Brothers (Nigeria Publishers) Limited.
• https://www.draftingtextbook.com/technical-drawing-sections

Instructional Materials

The teacher will teach this lesson with the aid of:

• Drawing board
• T-square and set squares
• Pencils (HB, 2H) and eraser
• Drawing paper
• Examples of building plans, elevations, and corresponding sectional drawings (chart, projector, or printouts)
• Ruler and protractor

Rationale for the Lesson

This lesson helps pupils understand how to read and create drawings that show the internal structure of a building. It enables them to visualize hidden components, which is important for accurate construction and avoiding errors on site.

Prerequisite/Previous Knowledge

Pupils have a basic understanding of orthographic projections, including plan views and elevations of simple building components.

Lesson Content/Board Summary

SECTIONS IN BUILDING CONSTRUCTION

Definition of Sectioning

Sectioning in building construction is the process of cutting through an imaginary plane of a building or component to reveal its internal structure. A sectional drawing shows what would be visible if a part of the building were cut away.

Importance of Sectional Drawings

• They show the internal arrangement and construction details of a building.
• They clarify the relationship between different building elements (e.g., foundation, walls, floor slabs, roof).
• They provide information about material thicknesses, heights, and levels that are not visible in plan or elevation views.
• They help in detecting and resolving potential clashes or errors in design before construction begins.

Types of Sections

• Cross-section: A section taken perpendicular to the longest dimension of a building or object. It typically shows the width and height.
• Longitudinal Section: A section taken parallel to the longest dimension of a building or object. It typically shows the length and height.

Interpretation of Sections

To interpret a section, pay attention to the following:

• Cutting Plane Line: This line on the plan view indicates where the section is cut and the direction of view (usually indicated by arrows).
• Materials: Different hatching patterns are used to represent different building materials (e.g., concrete, brick, timber).
• Dimensions and Levels: Sections show vertical dimensions, floor levels, roof heights, and foundation depths.
• Components: Identify elements like foundations, DPC (Damp Proof Course), floor slabs, wall types, lintels, roof trusses, and finishes.

Production of Sections (Drawing Procedure)

Producing a section involves projecting details from the plan and elevation views.

General Steps:

1. Position the Cutting Plane: On the plan view, draw the cutting plane line where the section is to be taken, indicating the viewing direction with arrows.
2. Project Vertical Lines: From every point where the cutting plane line intersects a wall, opening, or structural element on the plan, project vertical lines downwards onto the drawing sheet.
3. Project Horizontal Lines: From the corresponding elevation, project horizontal lines for all relevant levels (ground level, DPC, floor levels, lintel levels, roof plate level, eaves, ridge).
4. Draw the Ground Line: Establish the finished ground level.
5. Draw Foundations: Detail the foundation elements below the ground line, projecting from the plan and elevation details.
6. Draw Walls and Openings: Draw the walls cut by the section, indicating their thickness. Show any windows or doors that are in the line of sight behind the cutting plane.
7. Draw Floor Slabs and Roof Structure: Project and draw the floor slabs and roof structure, including beams, trusses, and roofing materials.
8. Add Details and Hatching: Include details like DPC, lintels, and apply appropriate hatching to represent different materials cut by the section.
9. Dimension and Label: Add key vertical dimensions, levels, and labels for important components.

Worked Example 1: Section through a simple wall

Given a plan and front elevation of a simple wall with a window:

1. Draw the cutting plane line through the wall at a desired point (e.g., through a window opening or solid wall).
2. Project all vertical lines from the cutting plane on the plan.
3. Project all horizontal lines from the elevation (e.g., ground level, window sill, window head, wall top).
4. Draw the foundation below ground level.
5. Outline the wall and the window opening.
6. Add a lintel over the window.
7. Apply hatching to the cut wall sections.
8. Add labels like “Ground Level”, “DPC”, “Window”.

Worked Example 2: Section through a simple building foundation

Given a plan and elevation of a building corner with a strip foundation:

1. Draw a cutting plane line through the foundation and wall on the plan.
2. Project vertical lines from the cutting plane intersections to establish the width of the foundation and wall.
3. Project horizontal lines from the elevation to show ground level, DPC level, and foundation depth.
4. Draw the concrete strip foundation, block wall, and concrete slab.
5. Indicate the damp proof course (DPC) at the appropriate level.
6. Apply hatching to the cut concrete and blockwork sections.
7. Label components like “Strip Foundation”, “Concrete Slab”, “DPC”, “Ground Level”.

Teaching Methods/Instructional Techniques

Discussion, Lecture, Demonstration, Question and Answer, Visual Aids

Instructional Procedures

Step 1: Introduction

Time: 5 minutes
Teaching Skill: Set Induction
Teacher’s Activity: The teacher greets the pupils and reminds them about orthographic projections (plans and elevations). The teacher then asks what they think is inside a wall or under a floor.
Pupils’ Activity: Pupils respond to the teacher’s questions and recall previous knowledge.
Learning Point: Pupils are introduced to the concept of looking inside a building component.

Step 2: Definition of Sectioning

Time: 7 minutes
Teaching Skill: Explanation/Definition
Teacher’s Activity: The teacher explains what sectioning means in building construction, using a simple model or diagram of a cut object to illustrate the concept.
Pupils’ Activity: Pupils listen attentively and take notes on the definition of sectioning.
Learning Point: Pupils understand the fundamental meaning of a section.

Step 3: Types of Sections

Time: 8 minutes
Teaching Skill: Classification/Illustration
Teacher’s Activity: The teacher explains and illustrates the difference between cross-sections and longitudinal sections using prepared diagrams of a simple building.
Pupils’ Activity: Pupils observe the diagrams, identify the types of sections, and ask questions for clarification.
Learning Point: Pupils can differentiate between cross-sections and longitudinal sections.

Step 4: Interpretation of Sections

Time: 8 minutes
Teaching Skill: Guided Practice
Teacher’s Activity: The teacher displays a prepared sectional drawing and guides pupils on how to interpret it, pointing out the cutting plane, materials, dimensions, and various components.
Pupils’ Activity: Pupils study the sectional drawing, identify key elements, and practice interpreting the details shown.
Learning Point: Pupils develop skills in understanding information presented in sectional drawings.

Step 5: Production of Sections (Drawing Procedure)

Time: 7 minutes
Teaching Skill: Demonstration/Instruction
Teacher’s Activity: The teacher outlines the step-by-step procedure for producing a section from a given plan and elevation, emphasizing the use of drawing instruments.
Pupils’ Activity: Pupils listen to the steps, prepare their drawing instruments, and observe how to set up the drawing.
Learning Point: Pupils understand the systematic process for drawing sections.

Step 6: Worked Examples

Time: 5 minutes
Teaching Skill: Practical Demonstration
Teacher’s Activity: The teacher demonstrates drawing a simple section (e.g., a wall section) on the board or using a projector, guiding pupils through each step of projection and detailing.
Pupils’ Activity: Pupils follow the teacher’s demonstration, attempting to draw along or taking detailed notes on the procedure.
Learning Point: Pupils gain practical insight into producing accurate sectional drawings.

Step 7: Evaluation/Review

Time: 5 minutes

Teaching Skill: Questioning/Assessment

Teacher’s Activity: The teacher evaluates the learning by asking the following questions:

1. Define sectioning in building construction.
2. State two types of sections.
3. Mention three pieces of information that can be obtained from a sectional drawing.
4. List three important steps in producing a sectional drawing.

Pupils’ Activity: Pupils answer orally and in writing.

Learning Point: Pupils demonstrate understanding of the lesson.

Step 8: Conclusion

Time: 2 minutes
Teacher’s Activity: The teacher summarizes the lesson by reiterating the importance of sections in conveying building information and assigns homework: “Draw a simple cross-section of a brick wall with a foundation, showing the DPC and ground level.”
Pupils’ Activity: Pupils listen to the summary and copy the homework assignment.
Learning Point: Pupils consolidate their understanding of the topic.

Lesson Keywords

• Section – An imaginary cut through an object or building to reveal its internal structure.
• Cross-section – A section cut perpendicular to the longest dimension of a building.
• Longitudinal section – A section cut parallel to the longest dimension of a building.
• Cutting plane – The imaginary plane along which a section is cut.
• Hatching – Patterns used in drawings to represent different materials.

Differentiation

For pupils who are struggling, the teacher will provide simpler plan and elevation views for sectioning practice and offer more one-on-one guidance. Advanced pupils will be challenged with more complex building components or asked to draw both cross and longitudinal sections of the same object.

Note for teachers using this lesson plan

Emphasize the practical application of sectioning in real-world building projects. Ensure pupils understand the relationship between the plan, elevation, and the resulting section. Encourage neatness and accuracy in drawing, especially with line types and hatching. Use physical models or 3D animations if available to enhance understanding of internal structures.