Lesson 6

Lesson 6: Why Plants Compete

Learning Objective

Understanding that competition is a form of interaction among living things

Syllabus Correlations

· Theme: Investigating Living Things

· Learning Area: Interaction Among Plants

· Learning Objective: Understanding that competition is a form of interaction among living things

Learning Outcomes:

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

· list factors that plants compete for;

· give reasons why plants compete with each other.

Concept(s) Introduced:

·Plants compete because of some factors and reasons.

Skills Covered:

· Observing, classifying, making inferences, interpreting data, making conclusions, comparing and contrasting.

Vocabulary/ New Words:

· basic needs, cacti, dehydration, desert, nutrient, reproduce offspring, space, sunlight, survival of the fittest, water

Value(s) Incorporated:

· Having an interest in and curiosity about the environment.

· Being diligent and persevering.

· Realising that science is a means to understand nature.

· Thinking rationally

Materials Needed:

For control experiment:

One tray

One pack of soil

Ten bean seeds soaked overnight

50 ml water

Worksheet

For experiment on space, nutrients and water:

One tray

One pack of soil

100 bean seeds soaked overnight

50 ml water

Worksheet

For experiment on sunlight:

One tray

One pack of soil

10 bean seeds soaked overnight

50 ml water

Worksheet

For activity:

Two similar trays

Twenty balsam seedlings

Two watering pots

Two pack of soil

Worksheet

Point(s) to Note:

Teaching Strategies
Set Induction	Recap the basic needs of plants. Guide pupils on the basic needs of plants by giving some examples. Ask pupils what will happen if the plants do not get enough sunlight, space, nutrients and water. Component: Introduction
Step 1	Competition among plants happens because the resources of their basic needs are limited. Ask pupils to observe that some trees are tall and some are short in the jungle. Emphasise that plants that survive the competition will grow healthily. Plants that do not survive the competition will be unhealthy and may slowly die. Component: Content 1 Show the video on the control experiment; explain to pupils the aim of this experiment is to find out what plants need for growing. In this experiment, plants get enough sunlight, water, nutrients and space. Emphasise that when plants get enough resources such as sunlight, water, nutrients and space, they will grow well and healthily. The height of the plants is almost the same. Tray A Number of leaves Height of the plants Show the video on an investigation of nutrients, space and water. The aim of this experiment is to find out what happens when 100 bean seeds have to compete with each other for nutrients, space and water although they have enough sunlight. What will happen to the plants? The plants have different heights. Some are tall and some are short. This is because the plants do not get enough space, nutrients and water to grow. Tray B Number of leaves Height of the plants Show the video on an investigation on sunlight. The aim of this experiment is to find out how plants compete with each other for sunlight as the plants are put indoors and near the windows. In this experiment, plants get enough water, nutrients and space but sunlight is limited. So the plants compete with each other for sunlight. The plants have different heights. Some are tall and some are short. This is because the plants do not get enough sunlight to grow. Tray C Number of leaves Height of the plants Component: Content 2
Step 2	Show the video on the different heights of trees in the jungle. Guide pupils to understand that trees grow very closely to each other. There is very limited sunlight reaching them. They need to compete for sunlight to produce their own food. The taller they grow the more sunlight they will get. So, some plants in the jungle are tall but some are short. Ask pupils to observe the roots of the trees. Mention to pupils that the roots of the trees spread over a very wide area. Explain that when there are limited nutrients in a place; bigger trees have roots that go deep into the soil in order to get nutrients and water. Component: Content 3
Step 3	Play the activity component. In groups of 5, carry out this interesting investigation. Grow some balsam seedlings using these steps. Two similar trays are prepared. Label them as A and B. Ten balsam seedlings are planted 4 cm apart in A. Ten balsam seedlings are planted 12 cm apart in B. All seedlings are watered with equal amounts of water daily. The number of leaves produced after four weeks is recorded. Pupils need to find out the relationship between the space between seedlings and the number of leaves produced. Count the number of leaves produced on each plant. Fill in the worksheet below. Prompt pupils to record other things they can measure on the growth of the plants such as height of the plants, colour of the plants and the width of the stems of the plants. Tray A B Number of leaves Component: Activity
Step 4	There are five questions in this component covering the learning outcomes. Questions 1 to 3 are objective questions. Q4 is a drag and drop activity. Pupils drag and drop the correct answers for the questions. Q5 consists of true or false questions. Pupils need to identify whether the statements are true or false. Use evaluation that will assess the pupils’ understanding of the lesson. Component: Evaluation
Step 5	Cacti compete with each other in a hot desert. They have longer roots to obtain water from the soil. Those with shorter roots die of dehydration. This is how plants compete for water in the desert. Component: Extension
Conclusion	Conclude the lesson by playing this component to further reinforce understanding of the lesson. Guide pupils to list the things that plants compete for and give reasons why plants compete. Prompt pupils to understand these factors that affect the competition among plants. Component: Summary