Class: Senior Secondary School 1 (SS1, SS 1, SSS1, SSS 1)
Term: 3rd Term
Week: 9
Age: 15 years
Duration: 45 minutes
Subject: Metal Work
Curriculum Theme: Pre-Vocational Studies
Previous Lesson: Cutting Speed, Feeds and RPM Calculations.
Topic: Reamers, classification of reamers and reaming practical.
Subject Matter: definition of reamers, classification into machine reamers and hand reamers, steps in reaming operation, practical reaming on pre drilled holes.

Specific Objectives

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

Cognitive Domain:

Define a reamer.
Classify reamers into hand reamers and machine reamers.
List the steps involved in a reaming operation.

Affective Domain:

Appreciate the importance of reaming for achieving precise holes.
Demonstrate care and proper handling of reaming tools.
Adhere to safety precautions during reaming operations.

Psychomotor Domain:

Identify different types of reamers (hand and machine).
Perform a reaming operation on a pre-drilled metal sample to achieve a smooth and accurate hole.
Select appropriate reaming tools for a given task.

Work cooperatively with peers during practical sessions.
Maintain a clean and organized workspace.

Reference Materials

The following resources were used in planning this lesson:

9 Years Basic Education Curriculum for Metal Work.
State Unified Scheme of Work for Senior Secondary Schools.
Basic Metalwork for Senior Secondary Schools by A.O. Alabi.

Instructional Materials

The teacher will teach this lesson with the aid of:

Hand reamers
Machine reamers
Drilled metal samples
Vise and wrench

Rationale for the Lesson

This lesson helps pupils understand how to achieve precise and smooth holes in metalwork, which is an important skill in various technical fields. Learning about reamers and reaming operations enables pupils to produce accurate components and use tools correctly for quality work.

Prerequisite/Previous Knowledge

Pupils should have prior knowledge of drilling operations and basic metalwork tools from previous lessons.

Lesson Content/Board Summary

Reamers and Reaming Operation

Definition of Reamers

A reamer is a multi-fluted cutting tool used to enlarge and finish a drilled hole to a precise size with a smooth surface finish. Reaming is performed after drilling to improve accuracy and surface quality of a hole.

Classification of Reamers

Reamers are generally classified into two main types based on their mode of operation:

Hand Reamers: These reamers are operated manually using a tap wrench or a reamer wrench. They typically have a slight taper at the front to help in guiding and starting the cut.
Machine Reamers: These reamers are designed for use with power-driven machines such as drilling machines, lathes, or milling machines. They are held in a chuck and rotated by the machine.

Steps in Reaming Operation

The following steps are involved in performing a reaming operation:

Select the correct size of reamer for the desired final hole diameter.
Drill a pilot hole slightly smaller than the desired final reamed size (e.g., 0.2mm to 0.5mm smaller).
Secure the workpiece firmly in a vice or appropriate fixture.
Mount the reamer (either in a wrench for hand reaming or in a machine chuck for machine reaming).
Apply cutting fluid (coolant) to the reamer and the hole to aid cutting and reduce friction.
Begin reaming by applying steady, light pressure and turning the reamer clockwise (for hand reamers) or starting the machine.
Never turn a reamer counter-clockwise while it is engaged in the hole, as this can dull the cutting edges.
Remove the reamer carefully once the full depth and desired size are achieved.
Clean the reamer and the reamed hole to remove chips and cutting fluid.

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, reviews the previous lesson briefly, and then introduces the new topic by asking questions about the need for precise holes in metalwork. The teacher displays various reamers and asks pupils if they know what these tools are used for.
Pupils’ Activity: Pupils respond to questions and observe the tools.
Learning Point: Pupils are prepared for the lesson and recall previous knowledge.

Step 2: Definition of Reamers

Time: 8 minutes
Teaching Skill: Explanation/Definition
Teacher’s Activity: The teacher explains what a reamer is, its purpose, and why reaming is performed after drilling. The teacher writes the definition on the board.
Pupils’ Activity: Pupils listen attentively, ask questions, and copy notes from the board.
Learning Point: Pupils understand the definition and function of a reamer.

Step 3: Classification of Reamers

Time: 8 minutes
Teaching Skill: Classification/Demonstration
Teacher’s Activity: The teacher classifies reamers into hand reamers and machine reamers, explaining the characteristics and uses of each. The teacher shows actual examples of both types of reamers.
Pupils’ Activity: Pupils observe the different reamers and note down the classifications and their features.
Learning Point: Pupils can identify and differentiate between hand and machine reamers.

Step 4: Steps in Reaming Operation

Time: 8 minutes
Teaching Skill: Demonstration/Explanation
Teacher’s Activity: The teacher explains and demonstrates the step-by-step procedure for a reaming operation using a drilled metal sample, a hand reamer, a wrench, and a vise. Emphasis is placed on safety and proper technique.
Pupils’ Activity: Pupils observe the demonstration carefully and ask clarifying questions.
Learning Point: Pupils understand the correct procedure for reaming.

Step 5: Practical Reaming

Time: 10 minutes
Teaching Skill: Practical Application/Supervision
Teacher’s Activity: The teacher provides pre-drilled metal samples, reamers, wrenches, and vises to groups of pupils. The teacher supervises as pupils attempt to perform a reaming operation, providing guidance and correcting errors.
Pupils’ Activity: Pupils carry out the guided reaming operation on the provided samples.
Learning Point: Pupils gain hands-on experience in reaming.

Step 6: Safety Precautions

Time: 3 minutes
Teaching Skill: Emphasizing/Reinforcement
Teacher’s Activity: The teacher reminds pupils of the important safety precautions to observe while using reamers and other metalwork tools.
Pupils’ Activity: Pupils listen and note the safety precautions.
Learning Point: Pupils are aware of the safety measures required during metalwork.

Step 7: Evaluation/Review

Time: 5 minutes

Teaching Skill: Questioning/Assessment

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

Define a reamer.
Mention two types of reamers.
State three steps involved in a reaming operation.
Why is reaming performed after drilling?

Pupils’ Activity: Pupils answer orally and in writing.

Learning Point: Pupils demonstrate understanding of the lesson.

Step 8: Conclusion

Time: 2 minutes
Teaching Skill: Summarization
Teacher’s Activity: The teacher summarizes the key points of the lesson, emphasizing the importance of reamers for achieving precision in metalwork. The teacher assigns homework, asking pupils to research different types of reamer flutes.
Pupils’ Activity: Pupils listen to the summary and copy the homework.
Learning Point: Pupils have a consolidated understanding of the topic and are given further tasks.

Lesson Keywords

Reamer – A multi-fluted cutting tool for enlarging and finishing drilled holes.
Hand Reamer – A type of reamer operated manually with a wrench.
Machine Reamer – A type of reamer used with power-driven machines.
Reaming – The process of enlarging and finishing a hole with a reamer for precision and smoothness.
Precision – The quality of being exact and accurate.

Differentiation

For pupils who grasp the concepts quickly, the teacher can challenge them to identify when specific reamer types would be more suitable. For pupils who require more support, the teacher will provide closer supervision during the practical session and offer one-on-one guidance.

Note for teachers using this lesson plan

Ensure all safety protocols are strictly followed during the practical session. Prepare the drilled metal samples in advance and have enough tools for group work. Emphasize the importance of choosing the correct reamer size and using cutting fluid.