Asteroids, comets and meteors
These three short online lessons discuss asteroids, comets and meteors.
These three short online lessons discuss asteroids, comets and meteors.
These two short online tutorials discuss how the earth rotates and then the earth's revolutions.
In the first URL, the YouTube video explains why earth has spring, summer, autumn and winter seasons. The second URL summarizes the key takeaway points.
Other objects in the solar system are discussed in this online textbook viz. asteroids, meteorites, comets and dwarf planets.
This 32 minute long YouTube video investigates the water contamination problems in Tanzania, with specific focus on Dar Es Salaam.
This 11 minute long YouTube video describes the various causes and types of water pollutants.
This YouTube video investigates what water pollution is and some examples and effects of water pollution.