Measurement Chapter Notes | Science Class 4 ICSE PDF Download

Introduction

Need for Measurement of Various Things

• Measurement is crucial in daily life for determining the size, quantity, or extent of objects.
• It is used in various activities, such as vendors measuring vegetables with a balance, milkmen measuring milk with a litre can, and tailors measuring cloth with a tape.
• Human senses alone are not reliable for accurate measurements.
• In ancient times, people used body parts like forearm, palm, foot, and hand for measurement.
• Ancient units included:
  • Cubit: Distance from elbow to the tip of the middle finger.
  • Handspan: Distance from the tip of the thumb to the little finger with fingers outstretched.
  • Foot span: Distance covered by one footstep.
  • Arm length: Distance from shoulder to the middle finger.
  • Arm span: Distance between the tips of middle fingers of both arms, held parallel to the ground.
• Body-based measurements were inaccurate because body part sizes vary between individuals.
• Standard units are necessary for consistent and accurate measurements.

Measurement of Length

• Length is the distance between two ends of an object.
• The standard unit of length is the metre (m).
• Other units include centimetre (cm), millimetre (mm), and kilometre (km).
• Metres are used for longer lengths, kilometres for very long distances, centimetres for short lengths, and millimetres for very short lengths.
• Tools for measuring length include:
  • Metre ruler: Used for general measurements.
  • Metre rod: Used by cloth dealers to measure fabric.
  • Measuring tape: Used by tailors for flexible measurements.
• These tools have markings in centimetres or inches.
• Fact: 2.5 centimetres equal one inch.

Measurement of Mass

• Mass is the amount of matter in an object, indicating how heavy or light it is.
• The standard unit of mass is the kilogram (kg).
• Gram (g) is another common unit for lighter objects.
• Heavy objects are measured in kilograms, while light objects are measured in grams.
• In the past, seeds, grains, and stones were used to measure mass, but these were inaccurate.
• Modern tools for measuring mass include:
  • Beam balance: Balances objects against standard weights.
  • Weighing machine: Shows mass on a display or dial.
  • Electronic weighing machine: Provides digital readings.
• Weighing balances are used by vendors to measure vegetables and fruits.
• Daily uses include weighing fruits, vegetables, and personal body weight.

Measurement of Capacity

• Capacity is the amount of liquid a container can hold.
• Common units are litre (L) for larger volumes and millilitre (mL) for smaller volumes.
• Smaller containers have less capacity, while larger ones hold more liquid.
• Tools for measuring capacity include:
  • Measuring cylinder: Used for precise liquid measurements.
  • Measuring beaker: Used for measuring liquid volumes.
• These tools have markings to show the volume of liquid poured into them.
• Daily uses include measuring milk, water, oil, and other liquids.

Measurement of Time

• Time is measured using clocks or watches.
• The standard unit is the second (s).
• Other units include minutes (min) and hours (h).
• In ancient times, people used the sun’s position to estimate time, which was inaccurate.
• Modern clocks and watches have a dial with numbers 1 to 12 and three hands:
  • Hour hand: Moves slowest, completes one round in 12 hours.
  • Minute hand: Completes one round in 1 hour.
  • Second hand: Moves fastest, completes one round in 1 minute.
• Time guides daily activities like waking up, going to school, working, and eating.
• Fact: 1 hour = 60 minutes, 1 minute = 60 seconds, 1 hour = 3600 seconds.

Measurement of Temperature

• A measures how hot or cold an object is.
• Units are degree Celsius (°C) and degree Fahrenheit (°F).
• A thermometer is used to measure temperature.
• A clinical thermometer measures body temperature with these steps:
  • Clean the thermometer with soap, water, or alcohol.
  • Shake it until the mercury is at or below the lowest mark.
  • Place the bulb under the tongue for 1–2 minutes.
  • Remove carefully without touching the tip.
  • Hold at eye level to read the mercury column.
  • The point where the mercury stops indicates the temperature.
• Normal human body temperature ranges from 97.7–99.5°F or 36.5–37.5°C.
• Doctors use thermometers to check patients’ temperatures, and we use them when feeling unwell.

Terms to Know

• Measurement: Finding the size, length, quantity, or degree of something.
• Standard unit: Fixed units used for accurate measurements.
• Length: Distance between two ends of an object.
• Mass: Amount of matter in an object, showing how heavy or light it is.
• Capacity: Amount of liquid a container can hold.
• Temperature: Measure of how hot or cold an object is.