Revision of JSS1 Topics – JSS2 Intermediate Science Lesson Note (First Term)

Revision of JSS1 Intermediate Science is a review of four topics: the scientific method, measurement, matter and energy, and the cell.

Behavioural objectives

1. State the five steps of the scientific method in order.
2. Give the S.I. unit and instrument for length, mass, time and temperature.
3. Name the three states of matter and describe each one.
4. Define energy and name its forms, including potential and kinetic energy.
5. Differentiate between unicellular and multicellular organisms.
6. State the differences between a plant cell and an animal cell.

What is the scientific method?

The scientific method is a step-by-step way of asking questions and solving problems using evidence.

• Idea: science is a way of finding answers, not only a book of facts.
• Comparison: it works like a detective solving a mystery.

What are the steps of the scientific method?

There are five steps: observation, hypothesis, experiment, result (data) and conclusion.

1. Observation: you notice something using your senses, e.g. the hibiscus plant in the shade is smaller than the one in the sun.
2. Hypothesis: you make a smart guess that can be tested, e.g. “I think plants need sunlight to grow tall”.
3. Experiment: you test your guess, e.g. one plant in the sun and one in a dark cupboard.
4. Result/Data: you measure and record what happened, e.g. how much each plant grew.
5. Conclusion: you decide whether your guess was right or wrong.

What makes an experiment fair?

• Same conditions: use the same type of plant, the same soil and the same amount of water.
• One difference: change only one thing, here the amount of sunlight.
• Measure: record the height with numbers and units.

Why must a scientist be honest?

• Wrong guess: if the result shows your hypothesis was wrong, report it as it is.
• Learning: a wrong guess still teaches you something new.

What is measurement?

Measurement is the use of numbers and units to state exactly how much of a quantity there is.

• Example: say “the water is 80 °C”, not “the water is hot”.
• S.I. units: the International System of Units lets scientists all over the world use the same units.

What are the common quantities, units and instruments?

• Note on temperature: we often use degrees Celsius (°C) in daily life, but Kelvin is the S.I. unit.

What are the useful conversions?

• Length: 100 cm = 1 m.
• Length: 1000 m = 1 km.
• Mass: 1000 g = 1 kg.
• Time: 60 seconds = 1 minute.

What is matter?

Matter is anything that has mass and occupies space.

• Examples: your desk, the air and your water bottle are all matter.
• Not matter: light and sound have no mass, so they are forms of energy.

What are the states of matter?

There are three states of matter: solid, liquid and gas.

How does matter change state?

• Melting: solid changes to liquid when heated, e.g. ice to water.
• Freezing: liquid changes to solid when cooled, e.g. water to ice.
• Evaporation: liquid changes to gas, e.g. wet clothes drying in the sun.
• Condensation: gas changes to liquid when cooled, e.g. water drops on a cold bottle.

What is energy?

Energy is the ability to do work.

• Seeing energy: we cannot see energy itself, but we can see what it does.
• Unit: energy is measured in joules (J).
• Conservation: energy is not created or destroyed, it changes from one form to another.

What are the forms of energy?

• Light energy: lets us see, e.g. sunlight.
• Heat energy: makes things warm, e.g. a cooking fire.
• Sound energy: lets us hear, e.g. a drum.
• Chemical energy: stored in food, fuel and batteries.
• Electrical energy: flows in wires, e.g. from NEPA/PHCN lines or a generator.

What are potential and kinetic energy?

• Potential energy: stored energy, e.g. a stone held high up.
• Kinetic energy: energy of a moving object, e.g. a rolling ball.

What are examples of energy changes?

• Electric fan: electrical energy to kinetic energy.
• Torch: chemical energy (battery) to light energy.
• Eating food: chemical energy in food gives the body energy to move.

What is a cell?

A cell is the basic building block of every living thing.

• Comparison: just as a house is built of bricks, plants, animals and humans are built of cells.
• Fact: your body is made of trillions of cells working together.

What are the common parts of a cell?

• Cell membrane: thin layer that controls what enters and leaves the cell.
• Cytoplasm: jelly-like fluid where the cell’s activities take place.
• Nucleus: controls all the activities of the cell.

What are unicellular and multicellular organisms?

A unicellular organism is made of one cell, while a multicellular organism is made of many cells.

What are the differences between plant and animal cells?

Plant and animal cells share the nucleus, cytoplasm and cell membrane, but plant cells have three extra features.

• Cell wall: only plant cells have it, and it makes them stiff and strong.
• Chloroplasts: only plant cells have them, and they make food from sunlight (photosynthesis).
• Vacuole: plant cells have one large vacuole, while animal cells have very small ones or none.

Evaluation

1. Mention the five steps of the scientific method.
2. What is the S.I. unit for mass?
3. Name the three states of matter.
4. Give one difference between a plant cell and an animal cell.
5. Define energy and give one example each of potential and kinetic energy.

Assignment

1. Write the steps of a scientific method investigation to find out if plants need water to grow. Include your observation, hypothesis, experiment, result and conclusion.