ICSE · Grade 6

Ch. 2: Physical Quantities and Measurement

Learn what physical quantities are, why we need standard units, the metric/SI system, and how to measure length and mass carefully — with conversions by powers of 10.

Meaning of physical quantity and measurement Need for standard units Metric system and SI units Length: tools, precautions, direct/indirect methods Mass vs weight and unit conversions
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Science tip: use Visual and Concept modes — diagrams and particle models help you “see” the idea, not only read it.
# Physical Quantities & Measurement — Super Simple A **physical quantity** is anything you can measure with **numbers**: - How **tall** are you? → **length** - How **heavy**? → **mass** - How **long** to school? → **time** - Body heat? → **temperature** ### Golden rule Every measurement has **two parts**: 1. A **number** (magnitude) — e.g. 35 2. A **unit** — e.g. metres Saying only “35” is silly — 35 what? metres? kilometres? bananas? ### Why standard units? If everyone used their own foot or handful of grain, doors would not fit and shops would cheat by accident. **Standard units** (like the **metre** and **kilogram**) are the same for everyone. > Use the **Interactive lab** above: practice the ruler, climb the metric ladder, and convert mass!

Topics in this chapter

  • Physical quantity
    Any physical property that can be measured using numbers (length, mass, time, temperature).…
  • Standardisation
    Measurement = magnitude + unit. Units must be accurate, universal, stable over time and place.…
  • Metric & SI system
    Metric system powers of 10. SI has 7 base units: m, kg, s, A, K, mol, cd.…
  • Length
    Horizontal length, height, width/breadth, distance. Ruler and tape. 0-mark alignment. Direct and ind…
  • Mass and weight
    Mass = amount of matter (kg). Weight = gravity force (changes). Convert t-kg-g-mg by 1000.…
  • Time & temperature
    Time in seconds; clocks. Temperature with thermometer (°C, K).…

Philosophy check

  • What is this civilization?
  • Why was it advanced?
  • How did cities work?
  • Where do we still see these ideas?
  • Exams — what will be asked?