When a solid changes directly into a gas, without passing through a liquid stage.
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A Twig Science
Glossary Film.
Key scientific terms defined in just 60 seconds using stunning images and concise textual...

The formation of solid crystals from a solution, or a cooling liquid or gas.
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A Twig Science
Glossary Film.
Key scientific terms defined in just 60 seconds using stunning images and concise textual definitions....

A suspension of very fine liquid or solid particles in a gas.
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A Twig Science
Glossary Film.
Key scientific terms defined in just 60 seconds using stunning images and concise textual definitions. Twig Science...

A substance that is able to flow freely.
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A Twig Science
Glossary Film.
Key scientific terms defined in just 60 seconds using stunning images and concise textual definitions. Twig Science Glossary Films reinforce...

Discover the forces at work underwater, which dictate why large boats float but small pebbles sink. Physics - Forces - Learning Points. The buoyant force is an upward-acting force determined by the weight of the displaced water. Ships...

Discover how different materials react to heat, and why this can be both useful and dangerous. Physics - Energy And Radioactivity - Learning Points. Temperature affects the size and shape of an object due to the expansion and contraction...

Discover the differences in evolutionary adaptation between dolphins and humans, which allow these marine mammals to move through water far more easily and efficiently than us. Physics - Forces - Learning Points. Dolphins can swim faster...

Unreachable by man, scientists have developed a complex experiment to demonstrate the heat and pressure at the centre of the Earth. Earth Science - Geology - Learning Points. The Earth's core is a dense ball of iron and nickel. To...

Water can either be a solid, a liquid or a gas. How does matter change state? Chemistry - Atoms And Bonding - Learning Points. Ice, liquid water and steam all consist of exactly the same molecules. Evaporation occurs when the temperature...

Find out how chromatography can be used to create the chemical 'colour fingerprint' of a substance. What are the two chromatography methods and how are they used to solve crimes? Chemistry - Atoms And Bonding - Learning Points....

Why and how do substances dissolve? Discover what happens when you create a solution. Chemistry - Atoms And Bonding - Learning Points. A solution is the mixture formed when a solid dissolves in a liquid. A solvent is a liquid that can...

In 1869, Russian scientist Dmitri Mendeleev created the Periodic Table, ordering the naturally occurring elements by their structure and properties. His Periodic Table changed the course of Chemistry forever, and even predicted the...

The land surface of the Earth accounts for 1% of its total volume. Travel from the core to Earth's surface, examining the layers that make up our planet. Earth Science - Geology - Learning Points. The Earth is made up of four layers. The...

Discover the role played by intermolecular forces in changing the state of matter between solid, liquid and gas. Chemistry - Atoms And Bonding - Learning Points. Intermolecular forces are the attractive forces between molecules....

What is the difference between solids, liquids and gases? How does each state behave? Chemistry - Atoms And Bonding - Learning Points. The kinetic theory of matter states that particles are in constant motion and there are forces of...

Electrolysis is fundamental to industrial processes. How was it discovered, how does it work and what are its uses? Chemistry - Reactions - Learning Points. The Chemist Humphry Davy developed the reaction we now call electrolysis....

Discover the damage caused by shockwaves and how they are created by supersonic speeds. Physics - Waves - Learning Points. Waves of high pressure are produced when something moves through a medium at supersonic speed. At supersonic...

We make slime using borax, water and food colouring. The slime is a non-Newtonian liquid. A non-Newtonian liquid can behave like a liquid or a solid depending on the pressure applied to it. Chemistry - Atoms And Bonding - Learning...

We create a polymer using cornflour and water called oobleck. Oobleck is a non-Newtonian liquid that behaves like a solid and a liquid. When placed on a speaker, the vibrations cause the polymer to constantly change its behaviour and it...

Halogens are hazardous to human life, yet they can also be very useful. How do they react when they meet other elements? Chemistry - Periodic Table - Learning Points. The halogens are the elements in Group 7 of the periodic table. The...

We use lemons and strips of zinc and copper to make a battery. First, strips of copper and zinc are added to one lemon and they are connected across a voltmeter. This is repeated, this time with more lemons and metal plates, until a...

We release carbon dioxide from a fire extinguisher against a dark cloth to see what happens. The expanding gas cools as it leaves the extinguisher, forming a visible dry ice solid on the cloth. As it warms, the carbon dioxide vanishes...

The central, usually hottest and densest, part of a larger structure, for example a star, planet or galaxy. A Twig Science Glossary Film. Key scientific terms defined in just 60 seconds using stunning images and concise textual...

Introducing the liquids whose behaviours seem to defy the accepted states of matter. What are they and why don't they behave as we predict? Chemistry - Atoms And Bonding - Learning Points. Newtonian liquids take the shape of their...