Integrated Science: Book 1A Unit 1 Introducing Science
1.1-1.6 Key points + Practice
The UT1 Integrated Science paper covers Book 1A Unit 1, Introducing Science, sections 1.1 to 1.6: learning about science (1.1), the practice of science (1.2), laboratory safety (1.3), laboratory apparatus (1.4), using measuring instruments (1.5) and basic practical skills (1.6).
🔬 1.1 Learning about science
Definition: Science is the study of phenomena and events in Nature through systematic observation and experimentation.
Branches of science: physics, chemistry, biology, astronomy, geology and medicine.
What science gives us, and its limits:
1. Scientific discoveries and inventions have greatly improved our quality of life.
2. However, they can also cause harm if they are not used properly.
3. Scientific knowledge can help in natural resource management.
4. Some problems cannot be solved using scientific knowledge.
5. Scientific knowledge is subject to change as new evidence appears.
Natural resources fall into two types:
Renewable resources: solar energy, wind, water, forests, fish, crops
Non-renewable resources: fossil fuels (coal, petroleum, natural gas), metal ores
Key point: the supply of natural resources on Earth is NOT unlimited.
本節生詞：systematic
🧪 1.2 Practice of science
Steps of a scientific investigation:
1. Observe
2. Ask questions
3. Form a hypothesis
4. Design and do experiments
5. Analyse the results
6. Draw a conclusion
Types of scientific investigation:
Fair test: change only one variable and keep all other conditions the same.
Classifying: group things by their shared characteristics.
Pattern seeking: look for patterns among things.
Model building: use a model to explain something that is hard to observe directly.
Key terms:
Independent variable: the variable you deliberately change.
Dependent variable: the result you measure.
Controlled variables: the conditions you keep unchanged.
🚨 1.3 Laboratory safety
A laboratory is a suitable place for doing experiments. Safety rules must be followed.
Hazard warning symbols:
Before doing an experiment, pay attention to the hazard warning symbols on the containers of chemicals, for example flammable, corrosive, toxic and oxidising.
The fire triangle:
Three conditions are needed for a fire to start:
1. Fuel
2. Oxygen
3. A high temperature
Putting out a fire (remove one side of the fire triangle):
1. Remove the fuel: for example, turn off the gas supply.
2. Cut off the oxygen: for example, cover the pan with a lid.
3. Lower the temperature: for example, cool it with water.
🧫 1.4 Laboratory apparatus
Common apparatus and their uses:
Test tube: to hold a small amount of substances for reactions
Beaker: to hold liquids
Conical flask: to hold liquids; easy to swirl
Measuring cylinder: to measure the volume of a liquid
Watch glass: to hold a small amount of solid, or to act as a lid
Dropper: to transfer a small amount of liquid
Heat-proof mat: to protect the bench
Tongs: to hold hot objects
Test tube holder: to hold a test tube while heating
Bunsen burner: for heating
Vertical section diagrams:
Sometimes we draw vertical section diagrams of the apparatus to show the experimental set-up.
True or False (commonly tested):
T We often use a pair of tongs to hold hot objects.
F A heat-proof mat is used for putting out a fire. (Correct: it protects the bench.)
T Conical flasks are available in different sizes.
F We usually use a spatula to stir liquids.
📏 1.5 Using measuring instruments
Measurements, instruments and units (must be memorised):
Length | half-metre rule, metre rule, measuring tape
Units: millimetre (mm), centimetre (cm), metre (m), kilometre (km)
1. Electronic instruments can be used for precise measurement, for example a laser measuring device.
2. A thermometer has a measuring range; choose a suitable one.
3. To measure the thickness of one sheet of paper: measure the total thickness of many sheets, then divide by the number of sheets.
4. When reading a measuring cylinder, the eye must be level with the lowest point of the meniscus.
Measuring methods (often tested):
1. Displacement method for the volume of an irregular solid: put the object completely under water; the rise in the water level is the volume of the object.
Example: water rises from 25 cm³ to 35 cm³, so the volume is 35 − 25 = 10 cm³.
2. To measure an object that floats (such as a foam cube), use a metal block to sink it so that it is completely under water.
3. To find the mass of a very light object (such as a paper clip), measure the total mass of several of them, then divide by the number.
4. Choosing suitable units: thickness of lenses in mm; length of a car in m; volume of a bottle in mL/cm³; mass of a chocolate bar in g; time for a 100 m race in s; temperature of hot chocolate in °C.
🔥 1.6 Basic practical skills
Dropper: used to transfer a small amount of solution in the laboratory.
Parts of a Bunsen burner and their uses:
Chimney: to direct air and gas to the flame
Air hole: to let air in
Collar: to control the size of the air hole
Rubber tubing: to connect the Bunsen burner to the gas tap
Base: to hold the chimney upright
Steps for lighting a Bunsen burner (must be memorised):
1. Put the Bunsen burner on a heat-proof mat.
2. Close the air hole.
3. Place a gas lighter just above the top of the chimney.
4. Press the button of the gas lighter and turn on the gas tap.
5. Open the air hole slowly.
Comparing the two flames:
Air hole closed: luminous flame - yellow, irregular in shape, quiet, lower temperature
Air hole open: non-luminous flame - blue, regular in shape, noisy, higher temperature
Conclusion: use the non-luminous flame for heating because its temperature is higher.
True or False (commonly tested):
F When lighting a Bunsen burner, you should turn on the gas tap first. (Correct: close the air hole first.)
T The Bunsen burner may strike back when the air hole is fully open.
T We usually use a non-luminous flame for heating.
📝 例題
例題 1：1. Write down the steps of a scientific investigation.
2. 'Changing only one variable while keeping all other conditions the same' describes which type of investigation?
1. Steps of a scientific investigation:
Observe → ask questions → form a hypothesis → design and do experiments → analyse the results → draw a conclusion.
2. This is a fair test.
In a fair test only one independent variable is changed; all the other conditions (the controlled variables) are kept the same, so any change in the result can be attributed to that variable.
例題 2：1. What three conditions make up the fire triangle?
2. Covering a burning pan with a lid puts out the fire. Why?
1. The three sides of the fire triangle:
fuel + oxygen + a high temperature.
All three must be present for burning to take place.
2. Covering the pan with a lid:
the lid separates the pan from the air, so the supply of oxygen is cut off.
Without oxygen the fire goes out.
(Turning off the gas removes the fuel; cooling with water lowers the temperature.)
例題 4：Why is it not suitable to measure the thickness of one sheet of paper directly with a ruler? What should be done instead?
Reason: a single sheet of paper is too thin. The error in the reading would be too large to give an accurate result.
Correct method:
Measure the total thickness of many sheets (for example 100 sheets), then divide the total thickness by the number of sheets to find the average thickness of one sheet.
For example: if 100 sheets are 10 mm thick altogether, one sheet is 10 ÷ 100 = 0.1 mm.