Term: 2^{nd} Term
Week: 11
Class: Senior Secondary School 1
Age: 15 years
Duration: 40 minutes of 5 periods each
Date:
Subject: Physics
Topic: Elastic properties of solids
SPECIFIC OBJECTIVES: At the end of the lesson, pupils should be able to
INSTRUCTIONAL TECHNIQUES: Identification, explanation, questions and answers, demonstration, videos from source
INSTRUCTIONAL MATERIALS: Videos, loud speaker, textbook, pictures
INSTRUCTIONAL PROCEDURES
PERIOD 12
PRESENTATION 
TEACHER’S ACTIVITY 
STUDENT’S ACTIVITY 
STEP 1 INTRODUCTION 
The teacher reviews the previous lesson on the states of matter 
Students pay attention 
STEP 2 EXPLANATION 
He defines and explains elasticity and states Hooke’s law.

Students pay attention and participates 
STEP 3 DEMONSTRATION 
He solves exercises on the elasticity of solids

Students pay attention and participate 
STEP 4 NOTE TAKING 
The teacher writes a summarized note on the board 
The students copy the note in their books 
NOTE
ELASTIC PROPERTIES OF SOLIDS
Elasticity is the ability of a substance to regain its original shape and size after being distorted by an external force.
HOOKES LAW
Hooke’s law states that Provided that the elastic limit of an elastic material is not exceeded, the extension of the material is directly proportional to the applied force or load.
F α e
F= Ke
Where
F= Force
K= Stiffness or force constant or elastic constant
e = Extension
Example:
Calculate the elastic constant of an elastic cord stretched by a loan of 8.0N by 250cm.
Solution:
F=8N
e = 250cm = 2.5m
F = ke
K = F
e
= 8
2.5
= 3.2 Nm^{2}
Example: A Spring extends to 1.86cm when a mass of 20g was hung from it, if Hooke’s law is obeyed. What is the extension when additional mass of 10g was hung, given that original length of the string is 1.0 cm.
Solution:
L2 = 1.86cm
L1 = 1.0 cm
M1 = 20g = 0.2N
M2 = 20 + 10 = 30g = 0.3N
e = L2 – L1
1.86 – 1.00 = 0.86cm
=0.0086m
For the first force,
F1 = 0.2N
e1 = 0.0086m
F1 = K e1
K = F
e
K= 0.2
0.0086
K = 232.56Nm^{2}
F2 = k e2
e2 = F = 0.3
k 232.56
= 0.0129m
EVALUATION: 1. Define elasticity
CLASSWORK: As in evaluation
CONCLUSION: The teacher commends the students positively