SHADOWS

People have always been fascinated by shadows because, although they are always with us, we can never catch them or touch them. For this reason, shadows are often found in games and stories. Do you remember the story of Peter Pan losing his shadow?

But what is a shadow’ It is the dark area caused by an opaque object blocking light. It has the same shape as the opaque object. Shadows appear because light travels in a straight line and cannot go round obstacles.

Shadows can gradually change shape. They get longer when the angle between the light source and the opaque object increases. They get shorter when the angle decreases.

Try this experiment: darken a room by turning off all the lights and closing the curtains. Then, turn on a lamp or a torch and put your hands close to the light source. Move your hands farther away to see how their shadows change shape. 

PERPETUAL MOTION (Waterfall by M. Escher 1961)

All the machines we use need energy to function: a television needs electricity, a car needs petrol, a sailing boat needs wind, a bike needs a person to push the pedals.

Throughout history, people have tried to invent a machine that, once it was started, would not need more energy to keep functioning. This type of machine is called a perpetual motion machine.

Many people have tried to achieve fame by inventing a perpetual motion machine. However, all their machines eventually stopped because the energy ran out. If these inventions had worked, they would have changed the course of history. 

MAGNETS TO PLAY

A funny experiment based on the magnetic force.

Make a fossil: a funny experiment

Plastic: a modern material

Plastic is an inexpensive and versatile material which is used to make many objects. For example, it is good for making containers because is resistant to chemical changes. It is also a good insulator since it does not conduct electricity.
There are different types of plastics, such as:

• Polystyrene, for making plastic bags.
• Expanded polystyrene, for packing and containers.
• Bakelite, an insulating material for making pot handles.
• Rubber, for making car or bikes tyres.
• Polyester, for making clothes.

However, not everything about plastic is good. Plastic is not biodegradable. This means it remains in nature for several hundred years, polluting the environment. To reduce this pollution, people have started to recycle plastics instead of just throwing them in the rubbish bin.

NATIONAL PARKS

National Parks are created in natural areas where one or more ecosystems are unspoilt by human activities . The plants and animals in these ecosystems are of special interest.
In National Parks, special steps are taken to protect the landscape, flora and fauna.
In 1872, the United States created the first National Park in the world: Yellowstone National Park. In Spain, the first National Park, Mount Covadonga, was created in 1918. It is now renamed the Picos de Europa National Park.
At present, there are fourteen National Parks in Spain. They offer the best examples of Spain´s natural heritage: Aiguestortes and Estany of Sant Maurici, the Cabrera Archipelago, Cabañeros, Caldera de Taburiente, Doñana, Garajonay, the Atlantic Islands of Galicia, Monfragüe, Ordesa and Mount Perdido, Picos de Europa, Sierra Nevada, Tablas de Daimiel, Teide and Timanfaya.

Fossils: Rocks that reveal the past

We can sometimes find fossils in rocks. They are the preserved remains of plants and animals that lived on Earth millions of years ago.
Palaeontologists are scientists who study fossils because they can give us information about climate and the environment in the past. For example, if you find the remains of marine animals in rocks, then this area was probably under the sea thousands of years ago.
Fossils can be plant remains, or remains of animal bones, skeletons or teeth.
Special fossils called "ichnites" are rocks with dinosaur footprints. These fossils can be found in various parts of Spain, in the Autonomous Community of Rioja, and in the provinces of Teruel and Soria.