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Procedure for Sun Shadow Activity: 1. WARNING! Never look directly at the soon as this can cause permanent damage to your eyes. 2. For this activity you will be working in pairs to observe the changes to shadows that occur on a daily, weekly, and monthly time scale. You will take observations of shadows over a three month period, recording data three times per week. On days that you observe, you will take three measurements per day, e.g. at 10am, noon, and 3pm. You can choose which times you take data but they must be spaced out throughout the day. 3. Once you pick which times to take data, you must use the same times to measure the shadows each day to ensure consistent data. Also you must pick a location where you will measure shadows, make sure that this location is not obscured by trees or buildings at the times you choose to observe. To recap, every observation must be taken at the same location, and every day you must take data at the same times. 4. Before you begin, record in your notebook what you believe the evolution of shadows will look like over the course of one day, of one week, and one month. We will see if your observations meet your expectations. 5. When you make your observation, you will have to choose which person will create the shadow and which person will measure, unless you and your partner are exactly the same height you will have to stay in your roles throughout the activity. On your first observation record the height of the person making the shadow, the location you pick, and the times you will observe. These will not change so record this data once in your notebook. 6. Record your data in a table like Data Table 1, the data, time, and shadow length should be written down for every observation. DATA TABLE 1 Date Time Shadow Length December 27, 2011 10:35 am 60.7 cm Supplies: One partner (work in groups of two) Two meters of paper ruler Notebook to record data Time: Multiple observation of the course of three months Question and Conclusions: 1. Look back at your initial thoughts, is it different from what you pictured in your mind in step 4. If so, how? 2. What conclusions can you make about how shadows change over the course of one day, one week, one month, and three months. Important Vocabulary to Know: Sun: The star that is the central body of the solar system, around which the planets revolve and from which they receive light and heat: its mean distance from the earth is about 93 million miles (150 million km), its diameter about 864,000 miles (1.4 million km), and its mass about 330,000 times that of the earth; its period of surface rotation is about 26 days at its equator but longer at higher latitudes. Shadow: A dark area or shape produced by a body coming between rays of light and a surface. Angle: The space (measured in degrees or radians) between two intersecting lines or surfaces at or close to the point where they meet. Horizon: The apparent line that separates earth from sky, the line that divides all visible directions into two categories: those that intersect the Earth's surface, and those that does not. More Online Resources: Shadow: http://en.wikipedia.org/wiki/Shadow Shadow: http://www.nasa.gov/audience/forstudents/k-4/stories/F_Keeping_Cool_With_Shadows.html