What do the Grade 8 General Science cards cover?

19 cards across 7 chapters of the national textbook: Basics of Scientific Investigation, Composition of Matter, Classification Of Compounds, Human Body Systems and Health, Ecosystem and Conservation of Natural Resources, The Solar System and Physical Phenomena in the Surrounding. You can take any chapter one card at a time on the page itself.

Do these help with the Grade 8 national exam?

Yes. Grade 8 sits a national exam, and these are the General Science rules and formulas it expects you to know. Past papers with a worked answer behind every question are on the same site, also free.

Where do these cards come from?

They are drafted from Grade 8 General Science, the Ministry of Education textbook for this grade. A second pass that cannot see the chapter then re-derives every formula, constant and table row, and anything it cannot confirm is held back instead of published.

Yes. Every card here is free to read and the printable sheet is free to download. Neither needs an account.

When was this last checked?

30 August 2026. Cards arrive chapter by chapter, and the line under each one says when that card was last read through.

Free short notes and revision cards

Grade 8 General Science

Grade 8 General Science on Temari has 19 revision cards, arranged by the chapters of the Ethiopian national curriculum. Every card says when the rule applies, what each symbol in it stands for, and the mistake students most often make with it. They are free to read and need no account.

19
Cards: 7
Chapters: 2
Formulas: 8
Reference tables: Grade 8 General Science
Textbook: Free
Price: 30 August 2026
Last checked

Everything19Reference table8Common mistake6Formula2Rule2Method1

Basics of Scientific Investigation

Accuracy vs PrecisionCommon mistake

When you use it

Use when distinguishing whether repeated measurements are close to the accepted true value or close to each other.

Watch out

High precision does not guarantee high accuracy. Measurements can be tightly clustered together while all being far from the true accepted value.

Drafted from Grade 8 General Science, pages 1-24, then checked twice before it went up

Fundamental Physical Quantities and SI UnitsReference tableLength · Mass · Time · +1

Fundamental Quantity	SI Unit	Symbol
Length	meter	m
Mass	kilogram	kg
Time	second	s
Temperature	kelvin	K

When you use it

Use when identifying base physical quantities and their standard SI units.

Watch out

The SI unit of Temperature is kelvin (K), not degree Celsius.

Drafted from Grade 8 General Science, pages 1-24, then checked twice before it went up

SI Prefixes and MultipliersReference tableMega · Kilo · Centi · +2

Prefix	Symbol	Decimal Multiplier
Mega	M	$1\,000\,000$
Kilo	k	$1\,000$
Centi	c	$0.01$
milli	m	$0.001$
micro	$\mu$	$0.000001$

When you use it

Use when converting between metric units of very large or very small measurements.

Watch out

Capital M stands for Mega (million), while small m stands for milli (thousandth).

Drafted from Grade 8 General Science, pages 1-24, then checked twice before it went up

Steps of Scientific MethodMethod

When you use it

Use when ordering or planning the sequential steps of a scientific investigation.

Watch out

A hypothesis must always be formed before testing, and during testing, keep all variables constant except the one being tested.

Drafted from Grade 8 General Science, pages 1-24, then checked twice before it went up

Composition of Matter

Mass Number and Atomic CompositionFormula

A = Z + N

A = Z + N

$A$: Mass number $dimensionless$
$Z$: Atomic number (number of protons) $dimensionless$
$N$: Number of neutrons $dimensionless$

When you use it

Use to determine the number of protons, neutrons, or electrons in an atom represented by atomic notation.

Watch out

Mass number is the sum of protons and neutrons, not protons and electrons. For a neutral atom, number of electrons equals atomic number Z.

Drafted from Grade 8 General Science, pages 25-37, then checked twice before it went up

Classification Of Compounds

Hydrocarbon Homologous SeriesReference tableAlkane · Alkene · Alkyne

Class	General formula	Suffix	Smallest carbon count
Alkane	$\text{C}_n\text{H}_{2n+2}$	-ane	$n = 1$
Alkene	$\text{C}_n\text{H}_{2n}$	-ene	$n = 2$
Alkyne	$\text{C}_n\text{H}_{2n-2}$	-yne	$n = 2$

When you use it

Use this to determine chemical formulas and IUPAC names for hydrocarbons based on the number of carbon atoms.

Watch out

Alkenes and alkynes start at n = 2, not n = 1, because multiple carbon to carbon bonds require at least two carbon atoms.

Drafted from Grade 8 General Science, pages 38-73, then checked twice before it went up

Inorganic Carbon ExceptionsCommon mistake

When you use it

Use this when classifying chemical substances as organic or inorganic compounds.

Watch out

Do not classify all carbon-containing substances as organic. Oxides of carbon (CO, CO2), carbonates, hydrogen carbonates, cyanides, and cyanates are inorganic compounds.

Drafted from Grade 8 General Science, pages 38-73, then checked twice before it went up

Human Body Systems and Health

Adult Human Dental FormulaFormula

\text{Total Teeth} = 2 \times (I_{\text{upper}} + C_{\text{upper}} + P_{\text{upper}} + M_{\text{upper}} + I_{\text{lower}} + C_{\text{lower}} + P_{\text{lower}} + M_{\text{lower}})

\text{Total Teeth} = 2 \times (I_{\text{upper}} + C_{\text{upper}} + P_{\text{upper}} + M_{\text{upper}} + I_{\text{lower}} + C_{\text{lower}} + P_{\text{lower}} + M_{\text{lower}})

$I$: Incisors per half-jaw $\text{teeth}$
$C$: Canines per half-jaw $\text{teeth}$
$P$: Premolars per half-jaw $\text{teeth}$
$M$: Molars per half-jaw $\text{teeth}$

When you use it

Use to calculate the total number of teeth from the standard human dental formula: I=2/2, C=1/1, P=2/2, M=3/3.

Watch out

The dental formula gives teeth count for one half of the upper and lower jaw. Always multiply the half-jaw sum by 2 to get the total number (32 teeth).

Drafted from Grade 8 General Science, pages 74-126, then checked twice before it went up

Artery and Vein Oxygenation ExceptionsCommon mistake

When you use it

Use when deciding whether a specific blood vessel carries oxygenated or deoxygenated blood.

Watch out

Not all arteries carry oxygenated blood and not all veins carry deoxygenated blood. Pulmonary artery and umbilical artery carry deoxygenated blood. Pulmonary vein and umbilical vein carry oxygenated blood.

Drafted from Grade 8 General Science, pages 74-126, then checked twice before it went up

Ecosystem and Conservation of Natural Resources

Biodiversity Conservation MethodsReference tableIn-situ Conservation · Ex-situ Conservation

Conservation Strategy	Location	Habitat Area and Mobility	Examples
In-situ Conservation	Inside natural habitat	Large habitat area, greater mobility	National parks, sanctuaries, biosphere reserves
Ex-situ Conservation	Outside natural habitat	Small artificial area, less mobility	Zoos, botanical gardens, seed banks, aquariums

When you use it

Use this table to distinguish between protection of wild species in their natural ecosystems versus artificial facilities.

Watch out

Botanical gardens and seed banks belong to ex-situ conservation because species are protected outside their original natural setting.

Drafted from Grade 8 General Science, pages 127-163, then checked twice before it went up

Biological Interactions in EcosystemsReference tableMutualism · Commensalism · Parasitism · +2

Interaction	Organism 1	Organism 2	Obligatory	Example
Mutualism	Benefited (+)	Benefited (+)	Yes	Fungi and algae
Commensalism	Benefited (+)	Unaffected (0)	No	Big tree and epiphytes
Parasitism	Benefited (+)	Harmed (-)	No	Human and tapeworm
Protocooperation	Benefited (+)	Benefited (+)	No	Teeth cleaning birds and crocodile
Competition	Harmed (-)	Harmed (-)	No	Two populations for resources

When you use it

Use this table to classify symbiotic and competitive relationships between organisms based on their benefit or harm.

Watch out

Mutualism is strictly obligatory for both species to survive, whereas protocooperation benefits both organisms without being obligatory.

Drafted from Grade 8 General Science, pages 127-163, then checked twice before it went up

Characteristics of Soil TypesReference tableSandy soil · Clay soil · Silt soil · +1

Soil Type	Particle Size	Water Holding Capacity	Agricultural Fertility
Sandy soil	Large particles	Poor	Low nutrient retention
Clay soil	Smallest particles, largest pore space	Highest	Poor drainage
Silt soil	Intermediate particles	Intermediate	Moderate
Loam soil	Mixture of sand, silt, clay, humus	Best balanced drainage	Most fertile

When you use it

Use this table when comparing particle size, drainage, water holding capacity, and fertility of soils.

Watch out

Clay holds the largest amount of water because of total pore space, but loam is the most fertile soil because it balances nutrients, moisture, and aeration.

Drafted from Grade 8 General Science, pages 127-163, then checked twice before it went up

Energy Flow Versus Nutrient CyclingCommon mistake

When you use it

Use this card when explaining the movement of energy and chemical nutrients through trophic levels in an ecosystem.

Watch out

Energy does not cycle. It enters as sunlight, flows in one direction through trophic levels, and is lost as heat, whereas chemical nutrients cycle continuously between organisms and the abiotic environment.

Drafted from Grade 8 General Science, pages 127-163, then checked twice before it went up

Steps of the Nitrogen CycleReference tableAmmonification · Nitrification (Step 1) · Nitrification (Step 2) · +1

Process	Input Substance	Output Substance	Responsible Microorganisms
Ammonification	Organic wastes and dead matter	Ammonium compounds	Decomposers
Nitrification (Step 1)	Ammonia	Nitrites ( $NO_2^-$ )	Nitrosomonas bacteria
Nitrification (Step 2)	Nitrites ( $NO_2^-$ )	Nitrates ( $NO_3^-$ )	Nitrobacter bacteria
Denitrification	Nitrates ( $NO_3^-$ )	Inert nitrogen gas ( $N_2$ )	Pseudomonas and Clostridium

When you use it

Use this table to trace the chemical transformations of nitrogen in the soil and the specific bacteria executing each step.

Watch out

Plants take up nitrogen mainly in the form of nitrates produced by nitrobacter, not directly as atmospheric nitrogen gas or toxic nitrites.

Drafted from Grade 8 General Science, pages 127-163, then checked twice before it went up

The Solar System

Hottest Planet in the Solar SystemCommon mistake

When you use it

Use when identifying the planet with the highest surface temperature.

Watch out

Do not choose Mercury simply because it is closest to the Sun. Venus is the hottest planet at 464 °C due to its thick carbon dioxide atmosphere that traps heat through the greenhouse effect.

Drafted from Grade 8 General Science, pages 164-186, then checked twice before it went up

Planetary Distance Size and Moon CountReference tableMercury · Venus · Earth · +5

Planet	Distance from Sun (million km)	Diameter (km)	Moons
Mercury	57.9	4880	0
Venus	108.2	12104	0
Earth	149.6	12750	1
Mars	227.9	6794	2
Jupiter	778.3	142984	79
Saturn	1432	120536	82
Uranus	2871	51118	27
Neptune	4498	49528	14

When you use it

Use when ordering planets by distance from the Sun, physical size, or satellite counts.

Watch out

Jupiter is the largest planet, but Saturn possesses the highest number of moons (82).

Drafted from Grade 8 General Science, pages 164-186, then checked twice before it went up

Small Solar System BodiesRule

When you use it

Use to distinguish between asteroids, comets, meteors, meteorites, and dwarf planets.

Watch out

A meteor is a small object burning up in Earth's atmosphere. If any unburned part lands on Earth's surface, it is a meteorite. Comet tails always point away from the Sun.

Drafted from Grade 8 General Science, pages 164-186, then checked twice before it went up

Physical Phenomena in the Surrounding

Properties of Magnetic Field LinesRule

When you use it

Use when sketching magnetic fields or solving questions on magnetic poles.

Watch out

Outside the magnet, field lines point from North to South, but inside the magnet they point from South to North. Field lines never intersect.

Drafted from Grade 8 General Science, page 187 onwards, then checked twice before it went up

Sound Speed and Propagation MediumCommon mistake

When you use it

Use when comparing the speed of sound across different states of matter or in a vacuum.

Watch out

Sound requires a material medium and cannot travel through a vacuum. Its speed is fastest in solids, slower in liquids, and slowest in gases, which is the exact opposite of light.

Drafted from Grade 8 General Science, page 187 onwards, then checked twice before it went up

The same subject in other years

An exam paper keeps asking for what the year below taught. Those cards are here too.

Grade 719 cards

Your other Grade 8 subjects

Everything else in this year that has cards so far.

Questions students ask

What do the Grade 8 General Science cards cover?: 19 cards across 7 chapters of the national textbook: Basics of Scientific Investigation, Composition of Matter, Classification Of Compounds, Human Body Systems and Health, Ecosystem and Conservation of Natural Resources, The Solar System and Physical Phenomena in the Surrounding. You can take any chapter one card at a time on the page itself.
Do these help with the Grade 8 national exam?: Yes. Grade 8 sits a national exam, and these are the General Science rules and formulas it expects you to know. Past papers with a worked answer behind every question are on the same site, also free.
Where do these cards come from?: They are drafted from Grade 8 General Science, the Ministry of Education textbook for this grade. A second pass that cannot see the chapter then re-derives every formula, constant and table row, and anything it cannot confirm is held back instead of published.
Is this free?: Yes. Every card here is free to read and the printable sheet is free to download. Neither needs an account.
When was this last checked?: 30 August 2026. Cards arrive chapter by chapter, and the line under each one says when that card was last read through.

Revise, then test yourself

Temari turns these cards into practice questions and marks them as you go, with an AI tutor to explain anything that did not land.

Start free