Teaching Prepared by Caroline W. Ndirangu

REFERENCES
LESSON 
ORGANIZATION
CONTENT
TEACHING/LEARNING ACTIVITY
INTRODUCTION
(  5 minutes    )
Different ways of introducing a lesson 
i.e
Review the previous lesson by asking 
questions.
•  State the need for 
movement of substances.
•  What is diffusion?
Question /Answer
POSSIBLE ANSWERS from the learners
Expected answers: to transport nutrients, remove 
waste products
Diffusion is the movement of molecules from a high 
to a low concentration until equilibrium is reached.
DEVELOPMENT
STEP 1.
 (5 minutes )
•  Describe osmosis as 
movement of water 
molecules from a low 
concentrated solution to a 
high concentrated solution 
through a semi-permeable 
membrane
•  Explain that it takes place in 
living tissues only.
 Teacher organises the learners into groups and 
guides the learners
Teacher illustrates osmosis using a chart.
  The learners set up the experiment on osmosis using 
the procedure below
•    Cut the potato cylinder into 2 cm pieces
•      Place 4 pieces in each of the solutions 
provided salty and distilled
•  Observe after 10 minutes
•   Draw the set up and Record observation
STEP 2.
( 15 minutes )
  
Explain the procedure of the 
experiment on osmosis.
 Teacher supervises the activity and guides the 
learners
  Learner writes down the procedure and also 
measure the potato cylinders after 10 minutes.
 Learners draw their own conclusions.
STEP 3.
 ( 5 minutes)
Explains the results of why cylinder 
in the salt was shorter and flaccid; 
cylinder in water was longer and 
turgid. 
 Inform learners the effect of osmosis 
in cells
 Learners report their findings as they discuss and 
record the group findings 
Learners take down notes

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African Virtual University
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CONCLUSION
(5 minutes)
 Recap of the lesson through 
question/answer technique:
1.Define osmosis
2.  What are its effects on living  
tissues
3. When do the cells loose and gain 
water?
 Teacher asks the learners questions to consolidate 
the lesson
1.   The process of osmosis water movement from a 
low concentrated solution to a high concentrated 
on through o semi permeable membrane 
Expected answers:
2.    Helps cells in living tissues to loose or gain water.
3.   Cells loose water when surrounding concentration 
is higher than the cell’s and gain when it has a 
lower concentration. than the cell.
ASSIGNMENT ( 2 minutes )
TITLE; Look up the terms hypotonic, hypertonic and isotonic in relation to osmosis
REF .Soper, R. and Smith, T.S., Biology for East Africa,( An Integrated Approach),(1986)London: Macmillan Ltd. Pages 
15-17
SELF EVALUATION ; done by the teacher after teaching the lesson
CAUTION: Note lesson notes are not lesson plans. Lesson notes are prepared 
separately 
Before writing a lesson plan of your own read through the following section on 
elements of a lesson plan. The section will guide you on what is expected in every 
stage of lesson planning. Use it to write your lesson plan in stages as you read 
through. Remember you can also go back to the format above and the compulsory 
readings on lesson plan in order to write a comprehensive lesson plan.