Term: Second Term / Term 2
Week : Week 5
Class : Primary 4/ Basic 4 / Grade 4
Subject : Agricultural Science
Topic : Dangers Involved in Excessive Use of Chemicals to Crops and Farmland.
Duration : 40 minutes
Previous Knowledge : Learners have been taught, ‘measure of applying chemicals to crops on the farm land.
Reference Materials : Agricultural Science for Primary Schools, Book 4.
Scheme of work for Upper Primary 4 – 6.
Online Resources
Instructional Materials : Charts showing spraying machine, Knapsack Sprayer, pesticides, herbicides.
Behavioural Objectives : By the end of the lesson, learners will be able to :
i. Identify the danger of excessive chemicals on crops
ii. Mention equipment used in applying chemicals
Content:
Weeds damage cultivated plants by competing with them for sunlight, water, and mineral nutrients. Some weeds are parasites that grow directly on other plants, and thus weakens or kill them. Many weeds are also hosts for disease-causing organisms.
Pest killing chemicals are synthesized or manufactured chemicals used in controlling pests on a farmland. A pest is any organism that is capable of causing economic damage to plant. There are different categories of pests among which are: insect, bird, monkey, rodents and man.
The chemicals used to kill weed is known as herbicide while the chemical used to kill pest is known as pesticide.
The chemicals are sprayed on the farmland by using a knapsack sprayer, spraying pumps, and spraying machine.
A Spraying Pump
The knapsack sprayer and the spraying pump are used on a small scale of land.
The spraying machine is used on a large scale of land. The machine is mounted on a tractor and it is driven by a tractor to sprinkle the land with the require chemicals.
Effects of Excessive Chemicals on Crops.
1. It may kill the cultivated crops on the farm.
2. It is poisonous, hence it may affect the health of human and animals.
3. Some herbicide in the soil can migrate to the ocean through nearby streams or rivers, and kill living organisms in the ocean.
4. The chemicals kills susceptible beneficial insects that prey on insect pests.
5. The chemicals can pollute the farm and render it non-fertile.
Presentation Steps:
Step I: The teacher revises the previous topic with the learners by asking some questions in order to arouse their interest.
Step II: He / She introduces the new topic to the learners
Step III: The teacher then explains the dangers of excessive chemicals on crops the farm
Step IV: State the dangers of excessive chemicals on plants and the farmland.
Evaluation: The teacher reviews the lesson explained by asking the learners some questions as stated below:
Conclusion: At the end of the lesson, learners were able to answer the question correctly.