OUR SKELETON

All vertebrate animals have a skeleton.
The human skeleton is made up of 206 bones.
Bones have many important functions:

• They give the body shape.
• They support the body´s muscles.
• They support the weight of the body.
• They protect the vital organs. For example, the skull protects the brain. The ribs protect the heart and lungs. The spinal column protects the spinal cord. 

3 DAYS IN THE PROVINCE OF SALAMANCA

DAY 1: We enter the province of Salamanca at the city of Zamora, which is very close the border with Portugal. Here, we take a tour around the Arribes del Duero National Park. The river Duero flows through this deep canyon, which has vertical walls 162 kilometres long and up to 150 metres high.
DAY 2: From the park we continue through Ledesma until we reach the city of Salamanca, where we can see the river Tormes. there are two cathedrals in Salamanca. The Old Cathedral was built in Romanesque style in the 12th century. The most spectacular part is the tower, which looks like it is decorated with stone scales.
DAY 3. From Salamnaca, we continue to the town of Bejar. Then we go on to Candelario, one of the coldest and most beautiful villages in the province of Salamanca. The river Cuerpo de Hombre flows through here.

GEOGRAPHICAL COORDINATES

Imagine you want to travel by ship to the Canary Islands. First, you need to locate these islands on a map. Then you need to find their cardinal points. The principal cardinal points are north, south, east and west. There are other points between these: northeast, southeast and southwest.
Next, you need to know the exact location of the Canary Islands on a globe. To do this, you use geographical coordinates. These are a set of imaginary horizontal and vertical lines that help you to locate geographical locations.
The horizontal lines are called parallels because they are parallel to the Equator. The vertical lines are called meridians and go from pole to pole. We use parallels and meridians to determine the latitude and longitude of a place.
Latitude is the distance between any point and the Equator. Points to the north of the Equator are latitude north and points to the south are latitude south.
Longitude is the distance between any point on Earth and the Greenwich Meridian. Greenwich is a town in the United Kingdom. Points to the east of Greenwich are longitude east and points to the west are longitude west.

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.