A plank and a block of wood can become a lever system which makes it easier to lift heavy objects.
Pulleys help with lifting things too.
Levers make lifting easier.
The length of the lever and the position of the turning point, or ‘pivot’ are important.
Pulleys convert downward ‘pull’ into upward ‘lift’.
Pulleys reduce the effort needed to lift a load.
Levers and pulleys belong to that class of items known as simple machines.
Simple machines are able to multiply a force and control the direction and strength of the force to make moving objects easier.
They are able to concentrate the moving force to where it is needed.
How Big? How Small? is a video and lesson plan. There are three areas of focus for the child:
to help children to realise that size involves comparisons
to help children to appreciate the importance of comparisons in measurement
to help children to realise that measurement includes things such as distance, length, width, breadth, height, thickness, depth, weight/mass, surface area, volume, capacity, time, temperature, angle, speed etc ie a wide variety of types of measurements
Pushes and pulls can be of different strengths.
The size of a push or pull can be measured.
Measuring devices are needed to measure the force of pushes and pulls. Forces are measured in newtons.
Newtons (N) is the scientific unit of measurement used for measuring the strength of a force.
Instruments that can be used to measure force strengths are called ‘force meters’, and they are calibrated in newtons.
It takes about 4N (four newtons) to lift an average-sized book.
The ear is divided into three parts: the outer ear; the middle ear; and the inner ear.
The outer part of the ear funnels sound down the ear canal (a tube about three centimeters long) towards the middle ear where the eardrum is locate.
The eardrum vibrates when sound vibrations hit it.
The vibrations are then transmitted through three tiny bones in the middle ear known (because of their shapes) as the hammer, the anvil and the stirrup.
The stirrup bone pushes directly against the inner ear with is filled with fluid.
In the inner ear, the vibrations move through the fluid and cause tine hair-like cells to move.
These, in turn, are connected to other nerve cells which send messages to the brain.
Levers can make it easier to move things.
With some levers, the object to be moved is at one end of the lever and push or pull is exerted on the other end.
There are different kinds of lever but all levers need a point about which the lever can turn (the pivot).
Where the pivot is positioned is important.
Some types of lever convert a small force at one end into a larger force at the other.
The strength of the levering force is affected by the position of the pivot.
With some levers, eg. A nutcracker, the pivot (or fulcrum) is at the end and there are two lever arms which work together to get the job done.
Animal bodies are held in shape by their skeletons.
Skeletons are made from lots of bones.
Bones do not bend. Movement in skeletons happens at joints.
Muscles control movement of joints.
Muscles can only work by pulling on bones.
The muscles contract (shorten) as they pull.
Muscles usually operate as opposing pairs.
Like machines, our bodies consist of a framework with moving parts.
Joints are like turning points (or pivots) of levers.
One muscle, or a set of muscles, contracts and pulls on the bones to cause movement.
This muscle cannot push the bone back again, but another muscle, or a set of muscles, is used for this.
Cleaning dirty water can be investigated with simple equipment.
Some materials clean muddy water better than others.
Fine materials let the water pass through more slowly than coarse materials.
Various materials can be used to filter out particles present in water.
Some of these filtering materials include rocks, charcoal, sand, cotton-wool and cloth.
The closer together the filtering material is packed, the finer the particles that can be filtered out of it.
Looser materials remove large impurities; finer materials remove tiny impurities. The slower the ‘filtration’ speed, the cleaner the water becomes.
Sand does not make the water absolutely clean.
Arches are strong shapes.
The keystone at the center of the arch holds the arch in place.
Structural strength may be due to the construction material used and/or the structural design.
In an arch, all the forces are pushing on the base, the sides, between the stones and onto the keystone area.
These forces all balance out so the arch does not move.
There are many different designs of arch bridges and they can be constructed out of many different materials.
The use of an ‘arch’ as a strong building structure has a long history dating back to at least Greek and Roman times.
Growing Numbers is a video and lesson plan. There are four areas of focus for the child:
To help children to explain sequences / patterns.
To help them to learn to predict and check subsequent numbers in the series.
To base growing number sequences in practical materials in order to help children to understand and appreciate pattern and its importance in mathematics.
To help children begin to generalise from number sequences.
Most animals drive themselves along with powerful hind legs. Different animals use their legs in different ways.
Force from the muscle power is needed to make animals move. This force is transmitted to the ground by an animal’s legs.
The animal pushes, then they walk or run.
The force of the animal pushing on the ground is met by the opposing force of the ground pushing back.
Animals’ skeletons and muscles work just like our own human skeletons and muscles, although the way in which the skeleton structure is arranged has evolved in a way that suits each animal’s lie style and the environment in which it lives.
Objects fall to Earth.
Parachutes are designed to allow the human body and other objects to fall to the Earth slowly. Jumping without a parachute from an aeroplane would be a disaster.
Parachutes are very unstreamlined.
They increase air resistance and decrease the rate of fall.
Making model parachutes and dropping them is a good way of experimenting with air resistance.
Objects fall through air to the ground by the force of gravity acting on them. At the same time that gravity is pulling the falling object downwards, the air through which the object is falling is pushing upwards.
The more air that can be captured by the falling object, the slower will be its fall toward the Earth.
The cleaning of dirty water can be investigated with simple equipment.
Passing dirty water through materials are better at cleaning than others.
Different materials can be used as ‘filters’ and can include rocks, charcoal, sand, cotton-wool, and cloth.
The closer together the filtering material is packed, the finer the particles that can be filtered out of it.
Looser materials remove large impurities; finer materials remove tiny impurities.
Testing materials and comparing results enables good filters to be identified.
Tests need to be ‘fair’ to ensure reliable results.
The choice of food may be affected by its color.
People may have different preferences of color for certain types of food. Most foods have natural color.
The color of food can be changed artificially with food coloring.
In this sort of test, the results may not be the same every time.
Taste buds are the receptors which determine our sense of taste.
These are nerve endings (about 10,000 of them) found on the tip, sides and back of the upper surface of the tongue.
Most experts use 4 taste receptors: sweet, sour, salty and bitter.
Each kind of taste bud is grouped in a specific location on the tongue.
For example, our ‘sweet’ taste buds are on the tip of our tongue, ‘salty’ on the side, ‘sour’ further back on the side, and ‘bitter’ right at the back of our tongue.
Water behaves as if it has a ‘skin’ around it.
Water clings to itself and to some objects and surfaces.
This ‘skin-like’ quality in the water’s surface is called ‘surface-tension’.
Surface tension operates in the surface of water.
It holds the surface together.
Water has a clinging effect both to itself and to some surfaces.
Because of the clinging effect, objects can be used to make water run in a particular direction.
Window ledges and other parts of buildings are often designed to make use of water’s surface tension, for drainage.
Playground equipment needs to be strong.
Strength depends on both the design and the material.
The design has to take into account the way in which the equipment will be used.
Playground equipment has to be fun, as well as safe.
It must also withstand the effects of weather.
In recent years a great deal of design thinking has been applied to playground equipment.
Some of the structures used are very imaginative, combining strength (and safety) with enterprise so that children will get enjoyment out of them. Playgrounds also provide good, and safe, opportunities for children’s physical development.
They engage in many strength building activities, develop motor skills, body awareness and physical confidence.
Owls use their ears as well as their eyes to locate their prey.
Some owls have ears which are slightly different from each other.
This enables them to locate pre with greater precision that if the ears were identical.
Such owls have evolved a hearing system which suits their life-style and the environment in which they live.
Owls that have asymmetrical ear openings, which are s paced widely apart, are able to determine the direction of a sound because it reaches each ear at a slightly different time.
This allows them to pinpoint a sound by a process of triangulation.
This can make an owl’s ear sensitive enough to detect the slight noise a mouse makes when running over twigs and leaves on the ground.
Some materials float in water naturally.
Other materials normally sink.
Sinking material can sometimes be made to float by changing its shape.
Boat shapes make good ‘floaters’.
Whether or not a material floats or sinks in water is due to that material’s density in relation to water.
Density is defined as the amount of particles of a material that occupy a particular volume of that material.
If a material’s density is greater than that of water, the material will sink in the water.
If the material’s density is less than that of water, the material will float.
Shapable materials that ordinarily sink, can be shaped to float on water.
As wax drips from one end, that end becomes lighter so the candle tips the other way. The motion speeds up as the candle gets shorter, rather like a pendulum which swings more quickly the shorter it is.
The candle begins rocking because of an imbalance of mass from one side of the candle.
The motion continues because each side of the candle alternately has a greater loss of mass making it, for a moment, lighter.
Making models of ‘real life’ machines is a good way of investigating how they work.
Machines need some form of power to make them work.
Simple materials can be used for making models.
Models do not always exactly mirror the real object.
‘Low technology’ may look simple, but it can be very efficient.
Machines can be made out of everyday, local materials.
Human populations and needs can frequently be answered by technology. The problem of getting a fresh supply of water can be lessened by the use of fairly simple devices.
Since a push is easier on the human frame to administer than a pull, machines that use pushes, rather than pulls, make our lives easier.
Animals that work for us are also pushing (against their harness) though people often see them as pulling.