CHAPTER 8 MIXING SUBSTANCES

Properties of Substances

Different substances have different properties. There are quite some substances that we use in our daily life, to name a few, salt, sugar, milk powder, baking powder and wheat flour. Properties of different substances can be stated in terms of:

Labels

• provide much of the information you need to know on how to use the substances safely
• may use signal words to show how toxic or hazardous (involving risk and danger) the substances can be either:
• 'Danger' means it is the most hazardous kind of material
• 'Warning' is less hazardous than Danger, but more hazardous than Caution
• 'Caution' is the least hazardous rating

Symbols

• show the harms that may be caused by the substances
• are one of the key elements of a safety label
• have the ability to communicate across language barriers

 There is always a need for kids to ask an adult before touching, smelling or tasting any unsafe substances. The unsafe substances should  be kept away in a place that is not reachable by kids. For adults, always look and read the labels or directions of usage carefully before handling any substances. It is better to be safe than sorry.

Separating a Mixture

What is a mixture? A mixture is two or more different substances physically blended together. There are several ways and techniques to separate a mixture, but in this post we only talk about the following methods:

magnetic attraction - using a magnet to attract magnetic substances from other non-magnetic substances

 Mixtures Separation Methods 

• sieving - using sieve to sieve through fine substances and retain substances with bigger particles in the sieve
• sink and float (by picking) - using a basin of water to separate light substances (which will float on water) and heavy substances (which will sink in water)
• filtration - using a filter paper to separate substances from a liquid (water) in which the substances is insoluble
• evaporation (heating under the sun) - used to separate a solute from a solvent in a solution

CHAPTER 7 SOILS

What is soil made up of ?

Soil is very important to us because it supports plants.  Many small animals live in the soil.  Let us find out what soil is made up of.  Soil is made up of humus, clay, silt, sand and small stones.  Humus is the layer on top of the soil surface.  It is black.  It is formed by decaying dead animals and plants.

The flow of water through different types of soil

There are three main types of soils.  These three types of soils are different in terms of the size of the soil particles.  They are sand, garden soil and clay.  Sandy soil are yellowish in colour. It contains a lot of air space and are grainy texture.  Garden soil are brown or balck in colour. It contains some air space and are soft and moist texture. Clay soil are red, brown or grey in colour.  It contains very little air space and are smooth and fine texture.

CHAPTER 6 ABSORPTION

Which Type of Materials Can Absorb Water?

Some materials can absorb water while some cannot. The materials that can absorb water are called "absorbent materials" and the one that cannot absorb water are called "non-absorbent materials".

Absorbent materials are:

• textile products that are made of cloth (cotton, silk, wool) for examples towels, handkerchiefs, t-shirts, undergarments, socks, jeans, denim, robes, traditional cloth diapers, shirts, ties, blouses, formal dresses, lingerie, pyjamas, kimonos, blankets, carpets, woolen garments and etc.
• objects that are made of cotton for examples cotton bud, coffee filters, cotton wool, face cotton, floor mop, thread and etc.
• objects that are made of wood for examples envelopes, toilet roll, books, tissue paper, newspaper and etc. Coconut-husk and tree trunk also can absorb water.
• other objects such as sponges (natural and synthetic) and feathers.

Example of absorbent material: 

Tissue paper

Non-absorbent materials are:

• objects that are made of metal for examples key, nail clipper, coin, tin can and etc.
• objects that are made of rubber for examples eraser, rubber gloves, tyre and etc.
• objects that are made of plastic for examples plastic pail, plastic bag, cutting board, rain coat, umbrella, tent, polystyrene container and etc.
• objects that are made of glass
• other objects such as pebbles, stones and marbles.

Example of Non-absorbent material:

Absorption Ability Are Differ from Materials to Materials

Different materials have a different ability to absorb water. Some materials can absorb more water than others. For example, a sponge can absorb more water than a roll of newspaper.

Experiment on Sponges

The ability to absorb water can also be differ from sponges to sponges and the following circumstances are taking into account.

• material - man-made sponges commonly made from cellulose wood fibres or foamed plastic polymers
• size - a large sponge can hold more water than a small sponge
• condition - a dry sponge can hold more water than a wet sponge because the wet sponge is closer to saturation and as such cannot hold more water. Sponges with more tiny holes can absorb more water than the sponges with less tiny holes
• fluid - the type of fluid being absorbed, water or water-based solutions

CHAPTER 5 SPRINGS

Spring

What is a Spring?

A spring is a device or an elastic object or a coiled piece of steel /other materials. A coiled spring also known as a helical spring.A coiled spring changes shapes when applied external force on it and return to its original shapes when force removed. If too much force applied, the coiled spring will permanently deform and will never return to its original shape.

Will a Spring Changes in Size & Shape?

Yes. A spring will change it size and shape when we:

• bend it - when a spring is bent, the size and shape of the spring are changed and when let go, the spring returns to its original size and shape;
• twist it - when a spring is twisted, the size and shape of the spring are changed and when let go, it returns to its original size and shape;
• squeeze/compress it - when a spring is squeezed/compressed, it becomes shorter and when the spring is released, the spring will return to its original length;
• stretch it - when a spring is stretched, it becomes longer and after being released, it returns to original length.

 

What Affect the Stretching Ability of a Spring?

• The length or diameter or thickness of a spring affect its ability to stretch more (easy to stretch) or less (difficult to stretch).
• Length. A longer spring is easier to stretch than a shorter spring. In other words, the shorter the spring, the less it stretches.

Diameter. A bigger diameter spring is easier to stretch than a smaller diameter spring. In other words, the smaller the diameter of the spring, the less it stretches.

Thickness. A thinner spring is easier to stretch than a thicker spring. In other words, the thicker the spring, the less it stretches.

Different weights of an object that hung at the end of a same spring will give different answer to its stretching ability. The heavier the object hung, the longer the spring stretches.

Basic Types of Springs

There are 3 basic types of springs.

Extension / Tension Spring

The coils normally touch together and when force applied to stretch the spring, the coils will separate. Examples of objects with the uses of extension/tension springs:

Source: Pohl Spring Works

baby hammock - to provide gently bouncing when baby was placed into it

stapler - to push the staplers forward and to keep the staplers in place;

spring balance - to measure weigh or force

Compression Spring

There are space between successive coils and when force applied to shorten the spring, the coils will push closer together. Examples of objects with the uses of compression springs:

Source: Pohl Spring Works

ballpoints pens - to push the nib in and out

pogo sticks - to bounce in a standing position off the ground

umbrellas - to extend or open it

toasters - to spring out the toast automatically when time out

mechanical pencils - to push the lead out

torches (battery holder) - to allow and hold the inserted battery

rocking horse - to allow it to move up and down

Torsion Spring

When force were applied to twist the coil, the spiral coil will be tightened. Examples of objects with the uses of torsion springs:

Source: Pohl Spring Works

mousetrap - to store energy and subsequently release it with the attached bar to pin a mouse to the base

clothes peg - to hold clothes tightly on a clothesline

clipboard - to hold papers tightly on the board

Other Objects with the Uses of Springs

mattress - to make it comfortable to sleep or sit on

vehicle - for suspension to allow a smooth and balance ride

office chair - to allow it to change the height of the chair

trampoline - to provide the rebounding force, such as to allow acrobats jump high into the air

CHAPTER 4 ELECTRICITY

What is the definition of “electricity”?

Electricity is a form of energy usually carried by wires or produced by batteries used to power machines and computing, communications, lighting, and heating devices.We use electricity every day. Appliances at home such as television, fan, water heater and refrigerator work when electricity flows through them in a complete circuit. An electric current does not flow through an incomplete circuit.

Diagram 1: A Complete Circuit

How Does a Bulb Lights Up Brighter or Dimmer?

A bulb lights up when electricity flows through a complete circuit which consists of a bulb, wires and a battery ( Diagram 1 ). Electricity flows from the positive battery terminal across a complete path toward the negative terminal.

Diagram 2: Bulb Lights Up Brighter

A bulb is brighter when more electricity flows through it. How? By adding one more battery to the circuit ( Diagram 2 ). The number of batteries used affects the brightness of a bulb in a circuit. But another battery further added to the circuit, the bulb will blow because there would be too much energy passing through the circuit.

Diagram 3: Bulb Lights Up Dimmer

A bulb is dimmer when less electricity flows through it. How? By adding another bulb to the original circuit ( Diagram 3 ). This is so because two bulbs sharing the power of one battery.

What Materials Conduct Electricity?

Some materials conduct electricity and some do not. Materials that conduct electricity i.e. allow electricity to flow through them are called conductors. All metals conduct electricity, for examples, silver, copper, gold, steel, tin, aluminium, iron and lead. Examples of objects which conduct electricity are as follows:

iron rod, silver spoon, 20-sen coin, gold ring, needle, paper clip, copper wire, aluminium foil, tin can, scissors, steel wool, iron nails, pencil lead, water and orange juice

Materials that do not conduct electricity i.e. do not allow electricity to flow through them are called non-conductors. Wood, plastic, cloth, rubber and glass are materials that do not conduct electricity. Examples of objects which do not conduct electricity are as follows:

matchstick, plastic comb, crayon, straw, chalk, paper, eraser, wooden ruler, glass, sponge, marbles, plastic spoon, toy, slippers, rubber band, button and cellophane tape

The Switch

A circuit must also contain a switch. A switch is used:

to stop the flow of electricity/current in the circuit by opening it (disconnect or break the circuit) 

( Diagram 4 ); or

Diagram 4: Switch Open, Bulb No Light

to allow the flow of electricity/current by closing it.

Diagram 5 : Switch Closed, Bulb Lights Up

The following are different types of switches:

Push Button Switch

  

Toggle Switch

   

         

Blade / Knife Switch

Twist Switch

On/Off Button Switch

CHAPTER 3 MAGNET

MAGNETS

Objectives
By the end of the lesson, pupils should be able to:

1.                  To know the types of magnets

2.                  classify the material attracted by magnets.

What is a Magnet?

That's a great question and one that you just might have to see for you to really understand. Be sure to do the science projects in this issue to learn how and why magnets work!

 What's the Attraction?

All magnets have the ability to attract other magnets or magnetic objects (such as iron and some other metal objects). But a magnet doesn't necessarily have to touch a magnetic object for the object to be attracted to it.

What Is a Magnet?

A magnet is a solid object, usually a rock or piece of metal, that has the ability to attract certain materials. To help discover what is and what is not attracted to magnets, go on a magnet hunt. Look around the room and help your child make a list of objects he or she thinks will be attracted to the magnet as well as a list of objects that will not be attracted. After making your lists, test each of the objects. (Don't use magnets on computers, cassette tapes, discs, and other electronic devices - it could damage the magnets inside of them!) Compare your results with what you predicted would be attracted. Were you correct on all your predictions? Were you wrong on any? Discuss why items did or did not stick when you originally thought the opposite would be true. For instance, the object is made out of plastic but coated with shiny paint to make it look metallic; not all metals are attracted to magnets; or maybe just parts of an object were attracted to the magnet. What does this tell us about magnetic attraction? (That an object must be made out of metal to be attracted, but not all metals are attracted.) Metals such as iron, nickel, and cobalt are attracted to magnets. Steel has iron in it, so it is also attracted to magnets.

As mentioned before, many common household items have magnets in them and are part of what makes these items work. Electronic devices such as refrigerators, washing machines, lamps, telephones, TVs, and stereos all have magnets in them.

Type Of The Magnets.

1. Bar Magnet

2. Cylindrical magnet

 

3. Horseshoe magnet

 

4. U-shaped Magnet

5. Ring magnet

6. Round magnet

Magnets Can Attract Or Repel Each Other.

1. When different poles of two magnets face each other, the magnets will attract.

 

2. When the same poles of two magnets face each other, the magnets will repel

CHAPTER 2 PLANTS

 EXTERNAL FEATURES OF PLANTS

Objectives
By the end of the lesson, pupils should be able to:

1. To identify the external features of plants
2. To group plants according to their external features
3. To group plants in various ways

 External Features of Plants

Plants have differents sizes, shapes and colours. They make our world a beautiful place to stay in.  Most plants have the same main parts: leaves, stems, flowers and fruits. However, these features do not look the same.

   Most plants heve green leaves.  However, some have yellow or red leaves.  Some leaves are shiny and some are dull.  the surface of leaves are smooth or rough.  The shape of leaves can be irregular, oval, round or needle shapes.

EXTERNAL FEATURES OF PAPAYA TREE

• SOFT STEM
• FLOWERING PLANT
• DULL LEAVES
• ROUGH LEAVES
• IRREGULAR SHAPE LEAVES

EXTERNAL FEATURES OF ROSE

• FLOWERING PLANT
• WOODY STEM
• OVAL SHAPE LEAVES
• THORNS
• SMOOTH AND DULL SURFACE LEAVES