Class: Senior Secondary School 1 (SS1, SS 1, SSS1, SSS 1)
Term: 3rd Term
Week: 4
Age: 15 years
Duration: 45 minutes
Subject: Metal Work
Curriculum Theme: Pre-Vocational Studies
Previous Lesson: Drilling Machines: Types and Reaming Operations.
Topic: Drills, part of drills, drill size.
Subject Matter: parts of drills, drill size identification, drill size in letters and numbers, drill shanks and their use, factors affecting drill choice.

Specific Objectives

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

Cognitive Domain:

Define a drill.
Identify and name the major parts of a drill bit.
Explain how drill sizes are identified and measured.
State the different types of drill shanks and their uses.
List at least three factors affecting drill choice for a specific task.

Affective Domain:

Appreciate the importance of using the correct drill size for accuracy and safety.
Value the proper handling and storage of drill bits.

Psychomotor Domain:

Draw a simple diagram of a twist drill and label its parts.
Select the appropriate drill bit size from a given assortment based on a specified requirement.

Collaborate with peers to identify and compare different drill bits and their sizes.

Reference Materials

The following resources were used in planning this lesson:

9 Years Basic Education Curriculum for Metal Work (Senior Secondary Education).
State Unified Scheme of Work for Metal Work SSS 1.
Basic Metal Work for Senior Secondary Schools by A.O. Okoro.
https://example.com/metalwork-drills
https://example.com/drill-size-charts

Instructional Materials

The teacher will teach this lesson with the aid of:

Assorted drill bits (twist drills of various sizes and types).
A drill size chart (showing metric, imperial, letter, and number sizes).
Sample workpieces made of different materials (e.g., wood, metal).
A diagram or poster showing the parts of a drill.

Rationale for the Lesson

This lesson helps pupils understand the tools used for making holes in materials, which is a common task in metalwork and other technical fields. Knowing about different drill parts and sizes enables pupils to choose the correct tool for specific jobs, leading to better results and safer practices in the workshop.

Prerequisite/Previous Knowledge

Pupils have basic knowledge of hand tools and workshop safety rules from previous lessons.

Lesson Content/Board Summary

Drills and Drill Sizes

Definition of a Drill

A drill, specifically a drill bit, is a cutting tool used to remove material to create holes of circular cross-section in various materials.

Parts of a Drill

The common parts of a twist drill are:

Shank: The part of the drill held by the chuck of a drilling machine.
Body: The main part of the drill, extending from the tip to the shank. It contains the flutes.
Flutes: Helical grooves that allow chips to escape and cutting fluid to reach the cutting edges.
Cutting Lips (or Edges): The sharp edges at the point of the drill that do the actual cutting.
Web: The thin central part of the drill body that separates the flutes. It extends from the point to the shank.
Point: The conical end of the drill where the cutting lips are formed.

Drill Size Identification

Drill sizes are defined by their diameter and are identified in several ways:

Metric Sizes: Expressed in millimetres (mm), e.g., 6mm, 10.5mm.
Imperial (Fractional) Sizes: Expressed as fractions of an inch, e.g., 1/4″, 3/8″.
Letter Sizes: A series of drills identified by letters A through Z, representing specific diameters, mainly used in imperial systems.
Number Sizes: A series of drills identified by numbers 1 through 80, representing specific diameters, mainly used in imperial systems for smaller holes.

Drill Shanks and Their Use

The shank is the part of the drill that fits into the drilling machine chuck. Common types include:

Straight Shank: Cylindrical in shape, commonly used for smaller drills and held in a drill chuck.
Taper Shank: Conical in shape, used for larger drills and fits directly into the spindle of a drilling machine or into a taper sleeve.

Factors Affecting Drill Choice

The following factors influence the selection of the correct drill bit:

Material to be Drilled: Different materials (e.g., steel, aluminum, wood, plastic) require specific drill bit designs and materials.
Hole Size: The required diameter of the hole dictates the drill bit size.
Type of Drilling Machine: The machine’s chuck capacity and power influence the largest drill shank and size that can be used.
Type of Operation: Whether it’s a through-hole, blind hole, or reaming operation affects drill choice.
Depth of Hole: Longer drills are needed for deeper holes.
Accuracy and Finish Required: Precision jobs may require specific drill types or reaming after drilling.

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 introduces the lesson by asking pupils about tools they use to make holes and shows different types of drill bits, asking them if they know what they are. The teacher then states the topic for the day.
Pupils’ Activity: Pupils respond to the questions and observe the drill bits. They listen attentively as the teacher introduces the topic.
Learning Point: Pupils are engaged and introduced to the topic of drills.

Step 2: Explanation of Drills and Their Parts

Time: 10 minutes
Teaching Skill: Explanation/Demonstration
Teacher’s Activity: The teacher defines a drill bit and uses a large drill bit or a diagram to explain and identify each major part (shank, body, flutes, cutting lips, web, point). The teacher writes the key terms on the board.
Pupils’ Activity: Pupils listen, observe, and identify the parts of the drill as explained by the teacher. They copy notes from the board.
Learning Point: Pupils understand what a drill is and can identify its main components.

Step 3: Demonstration of Drill Part Identification and Size Comparison

Time: 8 minutes
Teaching Skill: Practical Demonstration
Teacher’s Activity: The teacher passes around assorted drill bits and a drill size chart. The teacher demonstrates how to read the markings on the drill shank to identify its size and compares different sizes using the chart. The teacher also shows the difference between straight and taper shanks.
Pupils’ Activity: Pupils examine the drill bits, read the markings, and compare sizes with the chart. They observe the different shanks.
Learning Point: Pupils gain practical experience in identifying drill parts and sizes.

Step 4: Explanation of Drill Size Identification

Time: 7 minutes
Teaching Skill: Explanation/Questioning
Teacher’s Activity: The teacher explains the different systems of drill size identification: metric, imperial (fractional), letter, and number sizes, using the drill size chart as a visual aid. The teacher asks questions to ensure understanding.
Pupils’ Activity: Pupils listen, ask questions for clarification, and identify various sizes on the chart.
Learning Point: Pupils understand the different ways drill sizes are expressed.

Step 5: Explanation of Drill Shanks and Factors Affecting Choice

Time: 7 minutes
Teaching Skill: Lecture/Discussion
Teacher’s Activity: The teacher elaborates on the types of drill shanks (straight and taper) and their specific applications. The teacher then discusses the factors that influence the choice of a drill bit, such as the material to be drilled, hole size, and type of drilling machine.
Pupils’ Activity: Pupils listen and contribute to the discussion by suggesting other factors or asking questions.
Learning Point: Pupils learn about drill shank types and how to select the correct drill for a task.

Step 6: Practical Application/Group Activity

Time: 5 minutes
Teaching Skill: Collaborative Learning
Teacher’s Activity: The teacher divides pupils into small groups and gives each group a set of assorted drill bits and a task (e.g., “select a drill bit for a 10mm hole in mild steel” or “identify a straight shank drill”).
Pupils’ Activity: Pupils work in groups to identify drill parts, read sizes, and select appropriate drills based on the given tasks.
Learning Point: Pupils apply their knowledge practically and work collaboratively.

Step 7: Evaluation/Review

Time: 5 minutes

Teaching Skill: Questioning/Assessment

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

What is a drill bit?
Mention three main parts of a drill bit.
State two ways drill sizes are identified.
List two factors that affect the choice of a drill bit.

Pupils’ Activity: Pupils answer orally and in writing.

Learning Point: Pupils demonstrate understanding of the lesson.

Step 8: Conclusion

Time: 3 minutes
Teaching Skill: Summarization
Teacher’s Activity: The teacher summarizes the key points of the lesson, emphasizing the importance of correct drill selection and handling for safety and effective work. The teacher assigns homework: “Draw a twist drill and label its parts.”
Pupils’ Activity: Pupils listen to the summary and copy down the homework.
Learning Point: Pupils consolidate their learning and receive an assignment for reinforcement.

Lesson Keywords

Drill Bit – A cutting tool used to create circular holes.
Shank – The part of the drill bit held by the chuck.
Flutes – Helical grooves on the drill body that remove chips.
Cutting Lips – The sharp edges at the tip of the drill that perform cutting.
Metric Size – Drill diameter expressed in millimetres.
Imperial Size – Drill diameter expressed in fractions of an inch.
Taper Shank – A conical drill shank that fits directly into a machine spindle.

Differentiation

For pupils who grasp concepts quickly, the teacher can encourage them to research different drill bit materials (e.g., HSS, carbide) and their applications. For pupils needing more support, the teacher will provide more one-on-one guidance during the practical identification activity and use simpler language and more visual aids.

Note for teachers using this lesson plan

Ensure a variety of drill bits are available for demonstration and practical activities. Emphasize safety precautions when handling sharp drill bits. Encourage pupils to ask questions and share their observations during the practical sessions.