Science Class 6 Summary Notes



  • Parts of the male reproductive system include
  • Penis
  • Testis
  • Urethra
  • Sperm duct
  • Glands
  • Male parts
  • Female reproductive system
  • Parts of the female reproductive include
  • Ovary
  • Oviduct
  • Uterus
  • Cervix
  • Vagina
  • Female parts
  • Functions
  • Ovary-produce the ova after every 28 days
  • Oviduct-where fertilisation takes place
  • Uterus-where the foetus develop till maturity
  • Cervix-a ring of muscle that holds the foetus to maturity
  • Testis-they produce sperms
  • Urethra-allow passage of sperm and urine in men

Physical changes

  • In both boys and girls
  • Increase in height and weight
  • Hair appear in the armpit and the pubic area
  • Pimples may appear on the face
  • In boys only
  • The voice breaks
  • They experience wet dreams
  • The chest broadens
  • Girls only
  • The breasts enlarge
  • Voice become smooth
  • They experience menstrual flow
  • Hips broaden

Emotional changes

  • They mainly affect the feelings, they include;
  • Feeling shy
  • Embarrassment of,
  • Their height
  • Enlarged breasts
  • Wet dreams
  • Menstrual flow
  • Get moody very fast



They are diseases that a child is immunized against before they are 5 years.

  • Most of the diseases are dangerous if they infect a young child.

Immunizable diseases

  • They are diseases that one can be immunised against;
  • Typhoid
  • Yellow fever
  • Meningitis
  • Tuberculosis
  • Measles
  • Tetanus

Hiv and aids testing

  • Reasons of getting tested
  • To overcome fear
  • To stop the spread of HIV
  • To plan your future
  • To start medication early
  • To decide on marriage partner
  • To plan for your family
  • Pre-test counselling; it is the testing one receives in the VCT centre before being tested.
  • Post-test counselling; it is the testing one receives in the VCT after being tested

Effects of HIV/AIDS to the country

  • Reduced agricultural production
  • Poor economy
  • Death of skilled people
  • A lot of money is spent on treatment
  • Congestion in the hospitals

Effects to the family

  • Sadness in the family
  • Family income is spent on treatment
  • Children may become orphans
  • Children may drop out of school to take care of the sick parents
  • The family may feel discriminated.

Effects of HIV to the individual

  • Poor health
  • Poor performance
  • Spending of a lot of money
  • Feeling stigmatized



  • Main parts of a plant are;
  • Roots
  • Stem
  • Leaves


  • flower
  • The main reproductive part of a plant is a flower.
  • Parts of a flower include;
  • Male part
  • Female part

Functions of different parts;

Male parts

  • Anthers; produce pollen grain(male cells)
  • Filament; it supports the anthers

Female parts

  • Stigma; receives the pollen grains
  • Style; holds the stigma
  • Allow the development of pollen tube
  • Ovary; holds the ovules
  • Develops in a fruit
  • Ovule; female cell
  • Develops into seeds


  • it is the transfer of pollen grains from the anthers to the stigma of the same kind
  • Agents of pollination include;
  • Wind
  • Insects
  • water

Types of pollination

  • There are two types;
  • Self pollination-it is the transfer of pollen grains from the anthers to the stigma of the same plant.
  • Cross pollination-it is the transfer of pollen grains from the anthers to the stigma in different plants of the same type.

Characteristics of insect pollinated flowers

  • They have nectar
  • Brightly coloured
  • Have big petals
  • Sticky stigma
  • Small amount of pollen grains

Characteristics of wind pollinated flowers

  • Small in size
  • Dull in colour
  • Powderly pollen grains
  • Produce a large amount of pollen grains
  • Loosely attached filaments


  • It is the change of the seed into a seedling
  • Conditions necessary for germination
  • Air (oxygen)
  • Moisture(water)
  • Warmth(temperature)
  • Types of germination
  • Epigeal germination; the seed comes out of the soil during germination e.g. Beans
  • Hypogeal germination; the seed remains in the soil during germination e.g. maize
  • Types of germination
  • Hypogeal germination

Parts of a seed

  • Testa
  • Helum
  • Micropyle
  • Cotyledon
  • Radical
  • Plumule.


  • Venus is the brightest and the hottest
  • Mercury takes the shortest time to go round the sun
  • Mars is known as the red planet
  • Jupiter is the largest planet
  • Saturn has visible rings around it.
  • Asteroids are found in between mars and Jupiter
  • Planets ;smallest to largest


  • it is the process in which the Earth spins on its own axis
  • The Earth rotates on its own axis
  • The earth takes 24 hours to make a complete rotation.
  • The rotation cause day and night


  • It is the process in which the Earth moves around the sun.
  • The path that is followed by the Earth as it goes around the sun is called orbit
  • The Earth takes 365 ¼ days to make one complete revolution.
  • Revolution causes seasons


Animal Feeds

  • They are classified into
  • Pastures
  • Fodder
  • Conserved feeds
  • Commercial feeds
  • pasture
  • They are grasses and legumes that animals feed on directly. They are classified into;
  • Pure stand; only consist of either grass or legumes only
  • Mixed stand; consists of both grass and legumes


  • Examples of grass include;
  • Kikuyu grass
  • Star grass
  • Giant sataria
  • Rhodes grass


  • There are 4 main legumes used as pasture, they include;
  • Clover
  • Lucerne
  • Glycine
  • Desmodium.


  • They are crops that are hervestered or cut then given to the animals. examples;
  • Napier grass
  • Guatemala grass
  • Potato vines
  • Maize stalks
  • Kales
  • Sugar beet

Conserved feeds

  • They are animal feeds that are preserved in a special way to be used in future.
  • They are divided into two;
  • Hay
  • sillage


  • It is cut and preserved by drying
  • It is stored in bales


  • It is harvested when it is about to flower. It is preserved by fermentation.
  • It is stored when still green or in the succulent state.
  • It is stored in silos
  • The molasses is added to speed up fermentation.

Methods of grazing

  • Rotational grazing
  • Zero grazing
  • herding
  • Rotational grazing
  • They include
  • Tethering
  • Paddocking
  • Strip grazing


  • The animal is tied to a peg or post using a rope
  • The rope allows the animal to graze within a restricted area.
  • It is practised were few animals are kept


  • The land is divided into small areas known as paddocks using a permanent fence
  • A watering point is usually provided in each paddock.

Strip grazing

  • The animals are enclosed in a small portion of the pasture using a temporary fence.
  • An electric fence is usually used.

Zero grazing

  • It is also known as stall feeding
  • The animals are confined in a permanent structure (shed)
  • The shed should have feeding area, watering area, sleeping area and milking area.


  • It is a type of grazing where animals are allowed to graze freely on large areas of land.


Waterborne Diseases

  • They are diseases that are spread through contaminated water. They include:
  • Cholera
  • Typhoid
  • Bilharzia.


  • It is caused by bacteria. it can cause death within 24 hours if not treated. It causes death through dehydration.
  • Signs and symptoms
  • Violent diarrhoea (rice water).
  • Vomiting.
  • Severe abdominal pains
  • Wrinkled skin due to dehydration.
  • Sunken eyeballs


  • It mainly affects the intestines. It is also known as typhoid fever.
  • Signs and symptoms
  • Pain in the joints and muscles
  • High fever
  • Abdominal pains
  • Skin rash


  • It is caused by bilharzia worms or blood flukes. It is carried by water snails.
  • The disease mainly affect the bladder and intestines
  • Bilharzia worms enter the body through the skin.
  • Signs and symptoms
  • Blood in urine and stool
  • Coughing may occur
  • Abdominal pain
  • Swimmers itch
  • Fever


Soil Erosion

  • Soil erosion is the carrying away of the topsoil from one place to another.

Agents of soil erosion

  • They are things that carry soil from one place to another. They include;
  • Water
  • wind

Factors that influence soil erosion

  • Slope of land
  • Type of soil
  • Vegetation cover
  • Amount of rainfall
  • Human activities

Types of soil erosion

  • Splash erosion
  • Sheet erosion
  • Rill erosion
  • Gulley erosion

Splash erosion

  • It occurs when raindrops fall on bare loose soil.
  • It can be controlled by;
  • Planting cover crops
  • mulching

Sheet erosion

  • It occurs when water or wind carries away thin uniform layers of the topsoil.
  • It is not easily noticed
  • It occurs on gentle slopes.
  • Best controlled by;
  • Planting cover crops
  • Planting trees
  • Landslides are caused by sheet erosion

Rill erosion

  • It occurs when water flows down a slope and make small shallow channels. The channels are known as rills.
  • it is common on gentle sloping areas.
  • It can be controlled by;
  • Terracing
  • Contour farming
  • Strip cropping

Gulley erosion

  • It occurs when water make deep channels , they are known as gulleys
  • Gulley erosion leads to the formation of V-shaped or U-shaped channels.
  • It is common on bare hill slopes.
  • It can be controlled by;
  • Gabions
  • Porous dams
  • Check dams

Food and nutrition

Food Preservation

  • It is the process of storing and handling food properly so as to stop or slow down its spoilage.
  • Reason for preserving food
  • To reduce food wastage
  • T prevent it from being spoilt
  • For easy transport
  • To make food available when out of season.

Methods of food preservation

  • Food preservation is classified into;
  • Traditional methods
  • Modern methods

Traditional methods

  • They include;
  • Smoking- forms a coat
  • Drying- reduce moisture
  • Salting- reduce moisture
  • Use of honey- prevents oxygen
  • Use of ash- reduce moisture

Modern methods

  • Canning-killing germs and preventing oxygen
  • Refrigeration- low temperature
  • Freezing- low temperature
  • Drying is both a traditional modern method of preserving food. It is also the cheapest method of food preservation.



  • How light travels
  • Light travels in a straight line away from the source.
  • Light travels to all directions from the source.

Transparent materials

  • They are materials that allow all light to pass through them and one can see through them clearly.
  • Examples:
  • Clear glass
  • Clear water
  • air
  • Uses of transparent materials
  • They are used in making:
  • Car windscreens
  • Spectacles
  • Window panes
  • Lamps
  • Glass walls

Translucent materials

  • They are materials that allow only little light to pass through them.
  • Examples:
  • Frosted glass
  • Tracing paper
  • Oiled or waxed paper
  • Uses of translucent materials
  • They are used in making:
  • Skylights
  • Toilet and bathroom window panes
  • Ambulance windows.

Opaque materials

  • They are materials that do not allow any light to pass through them.
  • When light hits an opaque materials a shadow is formed.
  • Examples:
  • Wood
  • Stone
  • metals

Reflection of light

  • Reflection is the bouncing back of light when Materials that reflect light are called reflectors.
  • Reflection happens when light hits a smooth shinny surface.

Types of reflection

  • Regular reflection
  • Irregular reflection(diffused)
  • Regular reflection
  • Irregular (diffused)
  • Characteristics of the image in a plane mirror
  • The image is upright
  • The image is behind the mirror
  • The image is the same size as the object
  • The image is laterally inverted.

Refraction of light

  • It is the process in which light bends or changes direction when it moves from one medium to another. (air to water)

Effects of refraction

  • Objects appear bent or broken
  • Objects appear bigger
  • Swimming pool appear shallower
  • Making a rainbow
  • A rainbow is formed by the refraction of light. To be formed

raindrops and sunshine is required.

  • The process of splitting light into seven different colours is known as dispersion.
  • A group of seven colours in the rainbow is known as Spectrum.


Composition of air

  • Air is a mixture of gases
  • Air mainly consists of :
  • Gases
  • Water vapour
  • Dust particles
  • Components of air

Uses of oxygen

  • Breathing ( Respiration)
  • Germination
  • Burning ( Combustion)
  • Rusting.

Uses of carbon dioxide

  • Photosynthesis
  • Preserve soft drinks
  • To make fire extinguishers
  • Used in baking
  • Used in making dry ice.

Uses of nitrogen

  • Used by plants to make proteins
  • Used to preserve semen
  • It is taken in through the roots as nitrates. Leguminous plants are able to convert nitrogen to nitrates.

Uses of inert gases

  • They include Argon, Neon, Helium and Krypton
  • Used in electric bulbs and light tubes
  • Used in coloured advertising signboards.
  • Used in hot air balloons.



  • Force is a pull, push or lift.
  • It is measured in Newtons (N)
  • A moving object is said to be in motion while an object at rest is said to be stationary.
  • Force is measured by the use of a spring balance.
  • Examples of force
  • Force of gravity (weight)
  • Frictional force
  • Magnetic force
  • Inertial force

Effects of force

  • Makes an object to start moving
  • Stops a moving object
  • Change the direction of a moving object
  • Speeds up a moving object
  • Change the shape of an object.



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