A model car runs down a ramp towards a zebra crossing. By applying different combinations of front and back brakes children can investigate stopping distances on different surfaces.
Two pairs of large ring magnets are mounted on rods facing one another. One pair repel; the other attract. Pupils can place various materials between them. There is also a cluster of large magnets around which a number of small magnets and other materials can be turned.
Children can spin a number of tops which vary in diameter and thickness. They can fix small weights to them and observe the effect on their spinning.
Pupils can push a range of different-sized 'feet' into a foam rubber surface. The effort required to push down to the same degree shows the importance of the size of the area over which force is applied.
Children use a number of wooden blocks to create an arch bridge between two fixed supports. Another structure is used to show the importance of triangulation in giving rigidity.
Centre of gravity
You can test a variety of shapes some with weights attached to find their centre of gravity by trying to balance them on a pivot. You can also compare the stability of some model shapes with high and low centres of gravity..
Children make a pointer move in a specific direction by pulling on a combination of three strings. Another pointer like the hand of a clock is moved by pulling on a number of springs attached to each side - adding to or subtracting from each other.
Children place weights to balance a table pivoting at its centre. A spirit level shows when they get it right. They can also try to balance three different beams by moving their centres of gravity.
Direction of forces
You can lift a 'drawbridge' by pulling on strings passing through a 'castle wall'. The difficulty relates to the angle of pull. You can also cause a wheel to turn by moving a connecting rod attached to a slider.
Polarised light can be used to show the internal stresses of shapes as they twisted and pressed. You observe the significance of sharp and rounded corners in concentrating the stress lines.
Three identical springs can be stretched by pulling three cords. Each is attached to a different pulley arrangement, which determine the distance they have to be pulled and the effort required.
When a pendulum magnet is swung above other magnets set in movable blocks it responds to the attracting and repelling forces by moving erratically. A tray of iron clippings placed on the blocks shows their magnetic fields.