Cold and warm fronts are formed where bodies of cold and warm air meet.
Groundwater and aquifers are types of underground waters.
A periodic climate pattern that occurs across the tropical Pacific Ocean every five years.
The Crow are Native Americans who inhabited the Yellowstone River valley.
The world-famous limestone cave with its amazing cave paintings is one of the most important archaeological sites of Palaeolithic art.
The United States entered World War II after the devastating attack by the Japanese navy.
Tower cranes are machines used for lifting loads weighing up to several tonnes.
Division of space by three intersecting planes in several different arrangements.
The largest type of Arab sailboat, most commonly used as trading vessels in the Persian Gulf.
To calculate the volume of a tetrahedron we start by calculating the volume of a prism.
A long pipe in the centre of the tower penetrates the ocean bed until it reaches the layer that contains oil.
The masterpieces of ancient Greek potters are important archaeological artefacts.
Regular dice can be used for solving statistical and probability exercises.
The withdrawal reflex is a spinal reflex that ensures moving away from potentially damaging stimuli.
A hot air balloon is a balloon aircraft which is lifted by hot air.
Water turbines convert the kinetic energy of water into electric current.
This animation demonstrates the design and operation of a traditional cinema projector.
Domesticated animals and crops originate from various parts of the world.
This animation demonstrates the main sources of soil pollution.
Tardigrades can survive in extreme environments, they can even stay alive in outer space.