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.
Noise sounds different to people who cannot hear properly.
It is possible to get some sense of what it is like to be deaf.
There are many different degrees of deafness.
The degree of deafness may affect the quality and volume of noise that can be heard.
Simulating deaf or partial-hearing conditions can help in understanding how sound is interpreted and used by humans.
Hearing impairments afflict more people than any other chronic disability.
There are many different degrees of hearing impairment.
In some cases this can be temporary and in others it is permanent.
The most common form of permanent hearing impairment is otosclerosis which is caused by bony deposits that prevent sound vibrations from passing through to inner ear.
Most people with this form of hearing loss rely on a hearing aid which is a miniature microphone, amplifier and loudspeaker
A camera is a device that makes a ‘picture’ form on a screen.
The key parts are a small hole to let light in and a screen where the picture (or image) can form.
A pinhole camera does not give a permanent image (photograph).
The screen needs to be translucent so that the image can be viewed from the opposite side of the screen.
The image will always be upside-down.
Turning the camera upside-down will not bring the image the right way up. In most modern cameras, the shutter setting and the focus are automatically controlled.
In the pinhole camera the ‘shutter’ (the pinhole) is permanently open and there is no lens to focus.
To get a clear image on the screen it is necessary to move the screen manually back and forth to bring the image into view.
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.
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.
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.
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.
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 diving bell works on the same principle as an upturned glass of air pushed into water (see ‘Capturing Some Air’ and ‘Keeping Some Paper Dry’ lessons)
As long as there is air in the diving bell the water cannot enter. The diving bell must be heavy enough not to rise to the surface.
Getting a constant supply of fresh air into the diving bell is a problem.
Eventually the air becomes contaminated by the breathing of the people inside and has to be changed.
The first diving bell, designed by Edmund Halley, was a cone-shaped bell made of wood clad with lead.
This bell was sturdy and heavy, both to keep the air in and to help keep the bell submerged.
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.
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.
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
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.
Pushes and pulls make things move.
When two opposing pushes (or pulls) on an object are equal, movement stops. When something is still, all the pushes and pulls are balanced.
When forces are equal and opposite, no motion takes place.
In other words, if the ‘effort’ force is equal to the ‘resistance force’ there will be no motion.
If the opposing forces are pushing against or pulling against something with equal strength, the object will not move because the two forces are balancing each other.
If the forces acting on an object are unbalanced, it will move.
All movement depends upon forces being unequally balanced.
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 surface of water behaves as if it has a ‘skin’.
This ‘skin’ is strong enough to support light objects.
Some creatures are light enough to rest on the surface of water.
These creatures have adapted to a lifestyle which involves them making use of the surface of water.
Surface tension is strong enough to support creatures which have evolved ways of using the water-surface environment to suit the way in which they live.
Water clings to itself as if it has a ‘skin’.
This ‘skin-like’ quality at the water’s surface is called ‘surface tension’.
Surface tension is strong enough to support light objects placed on it.
Surface tension happens because the water molecules are strongly attracted to each other, and have a tendency to stay together.
This is why water forms globules or drops, flows in streams, and appears to have a ‘surface skin’ which can support light objects on its surface.
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.