6. Read the sentences and answer the question: "Paul and Steve did a lot of research about the deserts of North Africa at home, too. Their mother had bought them a globe which they loved to spin around to see how the colors- the green, blue, yellow and brown patches- became one big blur. During one of their after- school observations, they noticed that the map of the United States was about the same size as the Sahara Desert." What does the word "observation" mean as used in this text?