Point by Point ...

There are several ways to understand a concept. One of them is to "compare similar things point-by-point". Here is how you can do it,

• Collect a sample of similar things and make a list of their properties
• Which of the properties are similar ? Why ?
  
• Which of the properties are different ? Why ?
• Can you draw any generic conclusions from the comparison ?
  

If you collect roughly similar items then one can learn much by contrasting them with each other. If two things are completely dissimilar or completely similar then it dosen't tell much about their inner workings.

For example, in order to understand Earth's Atmosphere - you can compare Atmospheres of Mars, Earth and Venus - point by point. Look at their composition, structure, weather, ice, ocean cover, amount of Sunlight etc. This would generate a gut-level understanding of Earth's Atmosphere which is founded on a broader base.