Comprehensive reviewer for the National Achievement Test (NAT) Grade 6 — Science. It covers the most-tested skills with worked examples and test strategy.
Matter & Chemistry
| Type | Description | Example |
|---|---|---|
| Element | one kind of atom | Oxygen |
| Compound | atoms chemically joined | Water |
| Mixture | physically combined | Halo-halo |
Atoms have protons (+), neutrons (0), electrons (−). Atomic number = protons.
A compound is separated chemically; a mixture is separated physically (filtering, evaporation).
Living Things (Biology)
The cell is the basic unit of life. Know the organ systems, photosynthesis vs respiration, and genetics.
| System | Job |
|---|---|
| Digestive | break down food |
| Respiratory | gas exchange |
| Circulatory | transport blood |
| Nervous | control & response |
Plants make food via photosynthesis; animals are vertebrates or invertebrates.
Force, Motion & Energy
Energy forms: light, heat, sound, electrical, mechanical — and they transform from one to another.
Energy is conserved — it changes form, never disappears.
Earth & Space
Earth’s surface changes through plate tectonics (earthquakes, volcanoes). Weather is short-term; climate is long-term.
The Philippines sits on the Pacific Ring of Fire and in the typhoon belt — hence frequent quakes and storms.
The Scientific Method
| Variable | Meaning |
|---|---|
| Independent | what you change |
| Dependent | what you measure |
| Controlled | what you keep constant |
The independent variable is the CAUSE you change; the dependent variable is the EFFECT you measure.
Test-Taking Strategy
Many Science items test understanding, not memorization — reason from the concept. Use diagrams in the question. Eliminate options that are factually wrong before choosing.