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Even though molecules, proteins, viruses, and cells are all tiny, there are significant size differences between them. The diameter of a water molecule is roughly 0.28 nanometers. The diameter of the protein hemoglobin is roughly 5 nanometers. The diameter of the HIV virus is roughly 120 nanometers. A red blood cell is 6-8 micrometers.

This YouTube video elaborates on what weather is and what causes changes in the weather.

This fascinating video details the journey that a group of friends made in Nevada. Their aim was to illustrate the solar system to scale.

This YouTube video explores both passive and active solar energy.

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.

This short YouTube video introduces you to the planets which make up the solar system.

This online article delves into our the sun and planets were formed.

This online resource explores the following topics:

• Latitude and parallels
• Longitude and meridians
• Climate and latitude
• Time zones

This short online resource elaborates on the difference between climate and weather and why understanding the climate is important.

This online resource investigates the features and topology of the ocean floor, the effects of wave erosion and the landforms created by coastal depositions.