Eritrea Grade 8 National Examination cheat sheet

Area of a triangle = ½ × base × height; area of a trapezium = ½(a + b)h, where a and b are the parallel sides.

Pythagoras' theorem: in a right-angled triangle, a² + b² = c², where c is the hypotenuse.

Circumference of a circle = 2πr; area of a circle = πr².

Mean = sum of all values ÷ number of values; median = middle value when data are arranged in order.

To divide by a fraction, multiply by its reciprocal: a/b ÷ c/d = a/b × d/c.

Slope of the line through (x₁, y₁) and (x₂, y₂) = (y₂ − y₁) ÷ (x₂ − x₁).

Simple interest I = P × R × T ÷ 100, where P is principal, R is annual rate percent and T is time in years.

Sum of interior angles of a polygon with n sides = (n − 2) × 180°.

Probability of an event = number of favourable outcomes ÷ total number of equally likely outcomes.

Present perfect tense = have/has + past participle; it links a past action to the present.

Passive voice = form of be + past participle; the object of the active sentence becomes the subject.

In reported speech, present becomes past, will becomes would, and today becomes that day.

One-syllable adjectives form the comparative with -er and the superlative with -est; longer adjectives use more and most.

Relative pronouns: who for people, which for things, where for places, whose for possession.

First conditional: If + present simple, will + base verb, used for likely future results.

Subject-verb agreement: a singular subject takes a singular verb; a plural subject takes a plural verb.

A paragraph contains one topic sentence, supporting sentences and a concluding sentence.

Apostrophe rules: add 's for singular possession; add ' after the s for regular plural possession.

Photosynthesis: 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂, using sunlight and chlorophyll.

Speed = distance ÷ time; acceleration = change in velocity ÷ time taken.

Newton's first law: an object stays at rest or in uniform motion unless a net external force acts on it.

Density = mass ÷ volume, measured in g/cm³ or kg/m³.

Series circuit: same current through all components, voltage divides; parallel circuit: same voltage across branches, current divides.

Acids turn blue litmus red and have pH below 7; bases turn red litmus blue and have pH above 7.

Nucleus controls cell activities; mitochondria release energy; chloroplasts carry out photosynthesis.

Water cycle sequence: evaporation, condensation, precipitation, collection.

Food chain: producer → primary consumer → secondary consumer; energy decreases at each higher level.

Eritrea became independent in 1993; its capital city is Asmara.

Eritrea borders Sudan to the west, Ethiopia to the south, Djibouti to the southeast and the Red Sea to the east.

Lines of latitude run east-west, are parallel, and measure distance north or south of the Equator.

Lines of longitude run north-south and measure distance east or west of the Prime Meridian.

The three branches of government are the executive (implements laws), legislature (makes laws) and judiciary (interprets laws).

Rain shadow: the leeward side of a mountain is dry because descending air warms and holds more moisture.

Map scale 1:50,000 means 1 cm on the map represents 50,000 cm, or 0.5 km, on the ground.

Key latitudes: Equator 0°, Tropic of Cancer 23.5°N, Tropic of Capricorn 23.5°S.

Subsistence farming produces food mainly for the family; commercial farming produces crops mainly for sale.

A complete sentence needs a subject and a predicate and expresses a complete thought.

Adjectives and verbs must agree with the noun in gender, number and noun class where the language requires it.

Direct speech uses quotation marks and exact words; indirect speech reports meaning without quotation marks.

An idiom carries a figurative meaning different from the literal meaning of its individual words.

Active voice: the subject performs the action; passive voice: the subject receives the action.

A five-paragraph essay consists of an introduction, three body paragraphs and a conclusion.

Synonyms have similar meanings; antonyms have opposite meanings.

Comprehension questions ask for main idea, supporting details, inference and vocabulary in context.

Punctuation: full stop ends a statement, question mark ends a question, comma separates items or pauses.